AMENDMENT(11-Nov-2009):
To stop confusion for new readers of this thread, this project is panning out to be more of a
Data Acquisition / Engine Monitor / Emergency Shutdown Unit
for now anyway!
(End of amendment to post)
Guys I've been pondering about a DIY Data Acquisition and/or Auto Engine Controller for stationary engines for a long time.
After replying to a post elsewhere in this forum, I decided that its about time I do something about it and see if its possible to do it in a moderately easy way.
What I want to accomplish is a DIY "open source" Data Logging Unit to a PC and in the future I should be able to convert it to an Auto Engine Controller (with Logging in tact) by just changing the programming and minimal interface circuitry. I want to use regularly available building blocks for the system, ie. experimental boards & stuff that are normally well priced and there are a big following and code for them available from other peoples projects.
Just for reference I copied a section of my other post to here:This guy from the link below has done a lot of work on the subject with an electronic controller, but its quite involved and a lot of people (most) would not be able to do it, but if you read his pages, you get the general idea:
http://martin.nile.googlepages.com/automaticgeneratorcontroller (http://martin.nile.googlepages.com/automaticgeneratorcontroller)
Here is just a commercial auto engine controller:
http://www.fwmurphy.co.uk/products/engine_controls/engmot_asm150.htm (http://www.fwmurphy.co.uk/products/engine_controls/engmot_asm150.htm)
but its functions would be limited.
This product should do the job with a few censoring devices attached:
http://arduino.cc/en/Main/ArduinoBoardDuemilanove (http://arduino.cc/en/Main/ArduinoBoardDuemilanove)
I've done a bit of digging around on this Experimental USB Micro-controller and found the following:
They are available almost all over the world and cost effective,
There's a huge following of people using these on forums and such,
The programming software is Windows based & free,
Existing programming code can be copy/paste/stitched & loaded directly through USB port,
to name a few.
Here is a answer snipped from an email I wrote to a guy that supposedly knows:
"...these things can do pretty much anything. Don't worry about the code – there is so much available online you literally copy it and paste it into the arduino software, compile it and dump it via USB. The online community is SO helpful as well, there are arduino IRC channels we can recommend spending some time on too.
A good thing to do is go onto youtube and type exactly what you want – for example "arduino temperature monitor" etc, and most guys who post videos of projects also post links to code. Wherever you have a sensor, you can log data to wherever you want, even to the extent of being sms'd system failures etc.
From a flexibility and expandability point of view, the duemilanove is ideal for what you want. Like I said though, spend some time in forums, IRC channels, youtube and the Arduino site."
So, I ordered one and also 4x Temp. sensors. 1stly I want to see if I can hook it up to the 4 sensors and get it to log some temperatures of my WVO heating system to PC.
From what I understand it should go something like this:
Install the software,
Cut & Past existing code for a temperature sensor I found on the net into it,(its a little bit more involved than this, must duplicate it 4x, but you get the idea)
Connect my temp sensors to the Board,
Plug it into the USB port,
Compile and program the PIC.
and that should more or less be it, I should then be able to log 4x temperatures to my PC, all for +/- $53 including the temp sensors!
The main thing is that the project is only as good as the coding of the PIC and as nice as the User Interface on the PC.
What I need to know is what type of signals do we want to monitor on a gen-set?
Analog:
Temperatures ie. Water, WVO fuel in & out and maybe Exhaust if one can get a sensor for it.
Oil pressure for the Changfa guys ;)
AC Volts
AC Amps
Digital:(On/Off)
Low oil pressure
Low Fuel
Outputs:
Emergency shutdown
I'll worry about controlling a throttle later ;)
Anymore you guys can think of that I'm missing? I can then look around for code for these and also see how they may be interfaced with the board.
Obviously there are only so many I/O to use and I'll probably will have to prioritize.
This description is probably over simplistic and there's probably much more involved, but I have to start somewhere!
Any input is appreciated, thanks.
dubbleUJay
Quote from: Jens on October 21, 2009, 09:15:59 AM
RPM :)
BTW, $53 including 4 temp probes is exceptional !
Jens
The most important one!!! What was I thinking about ???, thanks Jens :-[
BTW, if I look at the pricing of same product from Sparkfun in America:(Just taking a common supplier)
1x Arduino USB Board $49-95
4x LM35 (degC) no stock, but should be about $2-00 @ most.
Don't know about postage over there though and there are probably cheaper suppliers.
The cheapest 4ch data logger I could find for $74
http://www.electronics123.com/s.nl/it.A/id.2693/.f
and that is ALL it can do!
dubbleUJay
Wow!
I really like what I am hearing so far! Is there really so much available code that we could actually do
as you suggest? That would be great! Please keep posting... I am very interested!
Rob
Quote from: rl71459 on October 21, 2009, 09:52:29 AM
Is there really so much available code that we could actually do
as you suggest?
Rob
Hi Rob, I found a few projects with code for temp. sensor and such, I need to "stitch" them together and get it to work.
I'm only starting out now (I haven't even got all the hardware yet), but I tent to learn quite fast ::) if I get the "flow" of things.
I've done a bit of coding a VERY long time ago, when ADT were still using EPROM's for there security alarm systems! Long before PIC's & stuff, but I should get the hang of it.
Obviously the user interface will be crappy in the beginning, but I'm hoping that if I can proof that it works, someone who knows what he's doing might offer to code a nice UI for Windows! ;)
The project should however be as easily as possible to duplicate. Hell, even the most basic "Low-cost Students Edition Data-logger" from National Instruments costs around $215 and then I need the upgraded software at $955 to do anything useful with it, that's $1170!!
http://sine.ni.com/nips/cds/view/p/lang/en/nid/14604 (http://sine.ni.com/nips/cds/view/p/lang/en/nid/14604)
Are they bloody mad ??? Very nice software and all, but not worth it for the average Joe like myself that wants to log some stuff on my Gen-set, wind-generator exec.
That money can pay for my 2x kids for a years school fees over here, "students edition's" @$$!
Anyway, that's just how I see things, they can go take their family 4 a ride ::)
dubbleUJay
Quote from: dubbleUJay on October 21, 2009, 09:33:47 PM
someone who knows what he's doing might offer to code a nice UI for Windows! ;)
I can't promise I know what I'm doing ::) but Windows UIs are "what I do" (has been for years), so I'm sure I could cobble something together. It would have to be in VB.Net though, I ain't about to learn C++ or Delphi now... ;D
;D
In the meantime if anyone cares to broaden their knowledge base. ::)
I'm currently looking at this project to get a few tips on how to interface with the sensors for Volts, Amp, Power exec., there a lot of interesting stuff:
Snipped: "This is a project to develop and build open source energy monitoring and analysis tools for energy efficiency and distributed renewable microgeneration."
http://openenergymonitor.org/emon/ (http://openenergymonitor.org/emon/)
How I never Googled myself into this site I dont know!!!
Like I said before, most of the stuff was already done, its just a matter of putting it all together in one project!
AdeV, thanks, I'll definitely push on your doorbell once I'm ready to get some UI going.
The more I read about this board, the more I like it, there is even wireless (ZigBee/XBee) options available, but 1st I need to do the basics.
I'll keep u's updated on the project, I'm just waiting for more hardware to arrive on Tuesday via ZA's "snail-mail" :P Here I go again, even eBay stopped using them because of corruption and theft, don't get me wrong, I love my country, just not the people who thinks their heritage gives them the right to do these things! >:(
dubbleUJay
I'm a programmer as well ( C++, C#, Java etc ) and this is very interesting to me.
I don't have a lot of free time right now but may be able to help.
I have a board that takes analog and digital inputs and sends them via TCP/IP to a main server where the data is stored in SQL Server, then you can trigger relays off the boards based on rules you dynamically set up which can be based on combinations of the inputs and date/time. Not sure it's affordable though!
OK guys, here a bit of an update:
I received all the hardware, 1x Arduino Board+USB Cable & 4x LM35 Temp Sensors.
Cost: R515 ZAR's (+/- $64) including the postage which was $12.50, so the hardware was about $51.50.
I'm using WinXP(SP3)
I installed the software & USB drivers,
connected 2 of the 4 LM35's to Analog inputs on the board,
copy/past some code for a 1 TempSensor from the web to the main Arduino software,
figured out how to duplicate it by 4,
sent it to the board,
hit the Serial Monitor button on the software,
and to my surprise, I got my four temperatures displayed in C&F in the window!
All in about 2 hours fiddling and I've newer done this before! ;D
The next step is to interface it with a real-time graph display program like KST (free as well)
http://kst.kde.org/download.html
At this stage I'm just following whats already been done by other people and bringing it all together.
Be sure to get the Win Binary version right at the bottom, for Windows obviously, but there's Linux and more as well.
This whole thing looks very promising.
Jedon/AdeV, most of the guys using this board seems to program applets in Java for it, which I know nothing about.
I manage to duplicate the 1 sensor code to 4TempSensors as it is so easy to understand what the code does. It's like "old" Basic to me in a sense.
Now, if YOU (or anyone else here for that matter) could perhaps get a basic board setup, imagine what we all could do! ;)
I don't get excited easily, but I honestly don't think you would buy a cat in a bag, because I think a 4xData Logging TempSensor alone would cost an arm and a leg and from what I've seen, this thing can just about do anything! You can just as well connect a photo-diode to it and know when the sun comes up. ;D There are Stepper controller code on the net as well and many more!
Any comment or suggestions ???
Here are a few screen-shots I took from the software, the graphing software are not my data.
Dubbleujay
Wow you are moving at light speed on this project, looks great.
Keep it up the forum is watching with great interest!!!!!!!!!
Billswan
Good Job WJ
I am looking forward to hearing about your progress. It is fantastic that it came together so quickly
even if it is only an initial attempt. I also am impressed with how little it costs!
Keep up the good work!
Thank You
Rob
I found this thread on the Arduino Forum:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1196965541
It seems like someone started something similar two years ago, but the "thread is dead" now!
It seem a bit overkill for what I was thinking, with "stand-alone" logging exec, but you might get a few tips there anyway, if someone cares to read it.
I'm still going through it at the moment.
Jedon, I'm sort of stuck with a Java program that reads the USB/Serial port info coming from the board. It reads it and log's it to a file where the Kst graphing program can get its readings from to O/P the graphs.
I found a Java applet that does it, but it seems to run under Linux and I'm using WinXP! :(
http://openenergymonitor.org/emon/sites/default/files/ArduinoCommTurbine.tar.gz
Snipped from the page:
"The ArduinoComm java program reads the values sent from the Arduino. The program outputs the values to the terminal window. Terminal is then used to write the printed data to a file for storage. The data file can be opened simultaneously by KST for real-time graphing"
Now this stuff I dont know how to do! YET anyway ;)
Any ideas???
dubbleUJay
Java compiles to bytecode that runs in the JVM ( Java Virtual Machine ) which is available for just about all platforms. That means that Java code is rarely platform specific and this should run fine on XP, I used 7-Zip to extract the source code so give that a whirl.
Hi Jedon, I also used 7-Zip, it extracts to a TAR 1st, then when I extract that, it tells me there's 2 files with the same name??? Program.java~
Apparently I then have to compile it, but I didn't go any further as I have the above mentioned problem!
I'm a novice & ignorant in this department, can the program not be pre-compiled and made available for download by the programmer?
dubbleUJay
Try the instructions here: http://www.arduino.cc/playground/Interfacing/Java
I wouldn't start with the code you posted, there isn't much there and it relies on external libraries which makes it hard to compile.
Start with their example and slowly tweak things, perhaps grabbing pieces of code from the project you found.
Quote from: dubbleUJay on October 29, 2009, 10:59:36 AM
Hi Jedon, I also used 7-Zip, it extracts to a TAR 1st, then when I extract that, it tells me there's 2 files with the same name??? Program.java~
That's usually the result of extracting without keeping the folder information; so the files "xyz\abc.txt" and "uvw\abc.txt" extract to the same place, hence errors.
WinZip deals with tar.gz files quite well; it will ask you if you want to extract the files from the tar straight into a directory structure (like "tar" on Linux does, given the appropriate incantations). You can download a free trial of Winzip, but I recommend going to http://www.oldversion.com/WinZip.html & getting either v9.0-sr1 or v10.0 - neither of which expire (they will nag you to buy, however).
Hi Guys,
The one I'm developing is written in visual basic.
Key readings will be monitored and logged by an old laptop near the machine.
When an event is triggered, the engine will be shut down and the software sends a message to my cell phone.
If all is well, an "OK" message is sent every 1/2 hour.
This enables me to leave it running while in the house or temporarily away from the site.
I already have routines written and tested for the cell phone messaging as well as the data collection part.
Next is the fancy graphical interface depicting the listeroid with actual values displayed in the over sized gauges.
Fun stuff,
Veggie
Quote from: veggie on October 29, 2009, 01:47:23 PM
If all is well, an "OK" message is sent every 1/2 hour.
That will annoy you in very short order... plus you'll find yourself scrambling to your phone every time you get a beep, just in case it's the engine breaking down...
Could you make it a "ping" system, i.e. you send a text to the engine controller, and it replies with its status?
At first, it will be every 1/2 hour. At any time I can change the settings. 1 hour, 3 hours....whatever.
I think I would prefer the engine to call me rather than waiting for me to ask. (I forget a lot ;) )
Veggie
Are you sending the SMS via an email gateway?
I use VoiceShot.com for this kind thing.
Quote from: veggie on October 29, 2009, 02:59:45 PM
At first, it will be every 1/2 hour. At any time I can change the settings. 1 hour, 3 hours....whatever.
I think I would prefer the engine to call me rather than waiting for me to ask. (I forget a lot ;) )
I was perhaps unclear (not for the first time!) - if any of your sensors went out of range, you'd get a text from the engine; but if it's all normal, a regular "Hey, I'm still normal" message will quickly become tiresome I suspect... Maybe wrong, I just know I get irritated at the WEEKLY status texts my mobile provider sends me...
Jedon,
Yes, I have programmed an SMS routine to send a message in SMS format to my cell phone service provider.
The software assembles the necessary text message based on if/then conditions dictated by the event such as high temp, overspeed, or whatever sensors one may have.
AdeV,
You are forgetting the "cool" factor. Chicks really think it's cool when a nerd get's messages from a machine ! :D
Seriously though, it's a matter of confidence. At first, leaving it running remote for 1 hour is a big deal to me.
Over time, as I get confidence in my shutdowns and monitoring ability, I would scale the "All clear" message to a greater time period.
There's always the ghost of having bugs in the software. So I would watch the system like a hawk until it proves itself.
Cheers,
Veggie
Quote from: veggie on October 29, 2009, 07:49:51 PM
AdeV,
You are forgetting the "cool" factor. Chicks really think it's cool when a nerd get's messages from a machine ! :D
Really ??? I must have been hanging around the wrong kind of chicks ::) All mine was ever interested in was shopping... :o
;D
Quote from: AdeV on October 29, 2009, 12:21:41 PM
That's usually the result of extracting without keeping the folder information; so the files "xyz\abc.txt" and "uvw\abc.txt" extract to the same place, hence errors.
WinZip...
Hi AdeV, I figured that was the problem, I tried WinZip, but still the same thing, I recon the folder structure are not in the TAR, but I might just be to flat-headed 2day! ::)
Anyway, after a lot of reading & cursing, I found this "interface" for the Arduino called GoBetWino (Yeh, what a name ;-), that does exactly what I wanted to do, ie write the date to file, and it does a lot more that I might need in the future, like write to the Arduino, email integration exec.
http://mikmo.dk/gobetwino.html
The UI is a bit simplistic, but after a while I got the hang of it, it looks like a sheep in disguise, but quite powerful once one reads the manual included in the download.
Now the next thing is to get the graphing recorder (Kst) to read from this file, but this "should" be easy apparently. ::)
I've been installing/uninstalling programs left, right & center trying to find the right solution! ;)
Once I have the basic programs in place and I'm recording data, I can start by expanding the Arduino hardware. (For now I'm still just recording 4x temp's as before just for testing)
I just want to make sure that the PC side of the project is do-able before I carry on with the fun stuff like interfacing the electronics. (In my books anyway)
An User Interface can always be done at a later stage once the electronics are working OK.
Maybe it was a blessing that I couldn't get the Java applet to work, we'll see, I'm off to bed, got a "VGA induced" headache like never before :-[ ;D
dubbleUJay
Another quick update 4 those that are interested:
I've now gotten to the stage where I can log 4x temperatures to a file on the PC and display it in real time on a graph.
I can now concentrate on the hardware interfacing as I cannot go much further with the software side of things without a steep learning curve in programming.
Next is to measure the AC Volts&Amps to calculate the power/frequency coming from a gen-head, (I've got a cct, just waiting for parts to arrive) and then engine speed directly from the flywheel of the engine. (I can calculate it from the gen hertz, but would rather have it from two sources.)
At some stage I would probably change the way I measure the temps to a 1-wire solution to free up some Analog ports on the controller for other uses.
I'm looking at monitoring the following for now:
1x Water Temp
1x HP Fuel line Temp (Maybe 2 places)
1x Exhaust Temp
AC Volts
AC Amps
AC Frequency (Calculate Engine speed)
AC Power used (Watts)
DC Volts
DC Amps
DC Power used (Watts)
Engine Speed from flywheel
A few Digital inputs for Low Fuel, Low Oil Pressure Exec.
Digital Outputs for Emergency Shutdown exec.
The controller side of the thing must be controlled/run/calculated by the board it self to work separate from the PC. The Data Acquisition side can work directly to PC, which can do the calculations. (Need to save as much space on the board's memory as possible)
Future features:
Governor control
A nice UI to display and store all these wonderful figures! ;)
Everything is out there on the web, its just a matter of finding them and putting it all together in one place! ::) There are probably a few more features, but these ones should keep me busy for a while.
Good work! I'll be sure to follow in your footsteps when I get time.
Does anyone know of a simple electronic cct to monitor exhaust temperatures other than using MAX6675 or AD595 K-type thermocouple chips?
I have a Thermocouple Probe (K-type from an old meter rated at over 1500degC), but the IC's to interface it are quite expensive and not available in ZA that I know of.
Also, if someone are going to build one in the future for this project, it might be to expensive, I want to keep costs down as far as possible!
I do not need accurate readings, just want to shutdown the engine at say 400degC, but also log to a precision of about 10degC, so a simple temp switch will not work, but might be considered if nothing else are available. It would be nice to log the temp though.
The LM35 and DS18D20 cannot read above 120degC :(
Amended/added:
What would you guys prefer to read the engine speed with, a magnetic pickup, IR reflective- or a IR "gap" distance sensor for counting the holes in the flywheel?
The latter seems less hassles as you do not have to put anything on the flywheel, but do all flywheels have holes ie changfa exec ???
WJ, An inductive sensor can sense flywheel spokes moving by, so will the Cherry brand (hall effect) gear tooth sensor. These both generate a digital pulse for each flywheel spoke. Many folks think IR or optical is a mistake in the dirty engine room. Given the other options, I agree.
If you must make it analog, then look at some frequency to voltage converter chips (F/V converter).
You could also modify the AC signal to feed a frequency to voltage chip, and avoid any extra sensing hardware, if your Lister is going to be dedicated to generator duty. (Mine does air compressor duty as well, so I added the gear tooth sensor as shown in the photo.)
Thanks Bruce, I would rather use a sensor on the engine like you and have the AC as a backup or "checking cct"
I will use a digital input to count the pulses and then do the calculations. I want to open my cam end cover to see if there might be an easy way to fit a hall-sensor to read the locking pin coming past or something to that effect, but I might loose accuracy due to the fact that its turning at half the crank speed.
On the other hand, this will aid me in another idea I have of a crude diesel "timing light" ;)
I use the basic "count" commad for 1 second for my 6 spoke flywheel sensor. It ties up the processor for the entire second on the Picaxe chip, but required zero hardware. I use the one second count delay as the main engine monitoring program loop time delay.
At 650 rpm with 6 spokes it works out just fine, there is just enough resolution for monitoring the starter spin up processes and adequate run time resolution.
Quote from: BruceM on November 10, 2009, 11:02:33 AM
At 650 rpm with 6 spokes it works out just fine, there is just enough resolution for monitoring the starter spin up processes and adequate run time resolution.
Thanks Bruce, that's whats so nice about talking to someone that's already done it, I didn't foreseen that the speed might be to slow on start-up to monitor it and would've learned this the hard way, once I've built a prototype already!
Can you tell me if/how you monitor your generator AC output i.e., Volts & Amps? I found a cct and modified it a bit as the original had problems with frying the isolation chips. It seems that they didn't build any protection into the cct as described in the application notes of the components.
I was thinking that these readings should be quite accurate, considering I want to work out real power generated with a set amount of fuel in the future.
Do you think that the way I want to generate the floating 5V supply will work if you look at the cct below?
I didn't want to go the Current Transformer way to monitor the generator as I thought it will be to involved, but now my cct is getting more & more complicated!
Its difficult to decide between cost, availability and simplicity at the same time, I can use and old "probe cct" I've got lying around here somewhere from years back for myself, but no one would be able to build one like it and that's defeating the object of this project. :(
My hand built AVR (not the simplified PCB version) does AC voltage monitoring, and the schematics have been posted below (see page eight). It's easiest to just use a tiny step down transformer (pcb mount), rectify, scale via resistor divider and RC filter. Or you can pay for a sensor $$
With my "fancy" AVR, voltage is either right on, or the AVR will disconnect power within an adjustable few seconds. So I only monitor the presence of AC power via 220V relay in my battery charge controller design. (Still in progress.)
For AC current monitoring , I'm using a NK self powered model A 100-1 AC current sensor which I found on ebay for $20. It's a current transformer that powers a 5V DC output. It can be jumpered for 10,20 or 50 amp scale, BUT the lowest current measurable is always 10%, thus 2 amps for 20 amp scale. This is fine for my needs- the battery charge controller just needs to see if there is enough "headroom" for the AC charger to operate.
There are other powered AC current sensors which provide full range measurement, and DC output. Or you can "roll your own" via CCT, with output rectified and filtered to get a DC signal which you can then scale as needed with a simple op amp.
The isolated op amps you show in your circuit are intended for measurement of DC current across a shunt, or for isolated DC measurement, not for measurement of AC.
Best Wishes,
Bruce M
Quote from: BruceM on November 11, 2009, 07:59:13 AM
My hand built AVR (not the simplified PCB version) does AC voltage monitoring, and the schematics have been posted. It's easiest to just use a tiny step down transformer (pcb mount), rectify, scale via resistor divider and RC filter. Or you can pay for a sensor $$
With my "fancy" AVR, voltage is either right on, or the AVR will disconnect power within an adjustable few seconds. So I only monitor the presence of AC power via 220V relay in my battery charge controller design. (Still in progress.)
For AC current monitoring , I'm using a NK self powered model A 100-1 AC current sensor which I found on ebay for $20. It's a current transformer that powers a 5V DC output. It can be jumpered for 10,20 or 50 amp scale, BUT the lowest current measurable is always 10%, thus 2 amps for 20 amp scale. This is fine for my needs- the battery charge controller just needs to see if there is enough "headroom" for the AC charger to operate.
There are other powered AC current sensors which provide full range measurement, and DC output. Or you can "roll your own" via CCT, with output rectified and filtered to get a DC signal which you can then scale as needed with a simple op amp.
The isolated op amps you show in your circuit are intended for measurement of DC current across a shunt, or for isolated DC measurement, not for measurement of AC.
Bruce M
Thanks Bruce.
I want to read the Vac from a scale say 150-250Vac and I also thought the easy way will be a transformer. Its just that I read about Vrms exec. and all the calculations involved from this site that originally designed the cct.
http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2008/cj72_xg37/cj72_xg37/index.html
I saw that its intended for DC, but they manage to use it for AC as it doesn't use the negative half of the AC signal.
Most of the code for the Micro is also already done on another site.
The same goes for the AC current, its one circuit monitoring both with the same type of IC.
I wont put this thing in line with my Mains utility power, but I recon for measuring my 3kW gen-head (220Vac 13A) it should be OK ??? (If it works, but as you can see from the site, apparently it does)
I can only stress again my intentions with this thing, I want someone else that want one, to be able to build it themselves from parts readily available from known suppliers.
It must also be modular, if you want to measure say 3 temps and DC volts, you can leave out the AC probe, or if you want 1x exhaust temp, 1x water temp and AC, you leave 2x temps and the DC probe exec.
I had an old auto engine controller before that connected to PC via RS232, which has burned out a while back. When I started shopping around for a new one, I was appalled at the costs and limited functionality.
I think that even if it costs as much as a commercial one to build (which I'm sure it wont) with all the probes and stuff, it would be 10x better in the functions it could do and one can change the programming at will as the Micro is a kit board well known everywhere.
dubbleUJay
WJ- I didn't realize you were attempting to do real time RMS calculation by sampling the rectified AC waveform.
This approach will pretty much require a dedicated processor just for the RMS voltage. The circuit from Cornell was set up for 120VAC, so some re-valuing of resistors (R1 in the original schematic) will be needed. Or your prototype has some wiring errors. I didn't check your schematic against the original, that would be a place to start.
I'm way too lazy to build one of such a thing when commercial devices to do it are available. My further advice- don't bother to "build for others"- in my experience there just aren't very many people capable of advanced hobby level electronics that will also want your gadget. I got very, very little response on the Basic AVR PCB.
Quote from: BruceM on November 11, 2009, 10:10:29 AM
I got very, very little response on the Basic AVR PCB.
I get my rig in December. Then I may need a "real AVR" Do you still have the PCB's and plans ?
You can order the PCBs from expresspcb.com with the file I can send you. It's $53/3. I don't have any.
Thanks again Bruce, it looks like I'm going to say those words a lot still in the future! ;) I hope I'm not bothering you to much with all the questions. (BTW, I was thinking of taking it to an Electronics forum somewhere, but I doubt if those guys will have the hands-on experience for Micro-Co-gen like this group ??? )
Comming back to the task at hand, the guy on the following site has taken Cornell's cct and converted it to 220Vac, his formulas are shown when you click on the links just below the circuit diagram on the site:
http://openenergymonitor.org/emon/node/2
He has the code for the ATmega as well on his site and this will save me a lot of hassles as I'm still learning the stuff. So even if no one is interested in it, at least I would have learned something that I should have done a long time ago. ;)
I looked at the suppliers application notes for the IC's and added the recommended protection to it and want to use an isolated DC to DC converter for the floating voltage as I didn't want an extra Wall-wart PSU. I figured that I will need a decent PSU at the end as the PC USB power wont cope with all the current when its finished, with all the probes and stuff connected, so I modified an old AT PC power supply to run everything in the end. I've got some decent 12 & 5V rails now and it plugs right into an old 400VA PC UPS!
I'll look at the wiring of my cct again, I could have easily made a mistake somewhere.
I get what your saying about others interests in building something like this, but I figured that we need something to do data logging with for our generators running on whatever. The controller side is more of a bonus if it can be done reliably with this board BTW.
A lot of the figures quoted everywhere are up in the air and the only way for me to proof it is to have reliable numbers.
For instance, if I can time-stamp plot my Load and Temp for a particular amount/type of fuel to PC, it makes it so much easier and accurate than fiddling with a meter and temp gauge, trying to write it all down at the same time at set intervals.
Anyway, that's how I see it, a lot of work now, but less in the future. I've got a saying around here: "Don't give me a hand-planer if you have an electric one in the cupboard, I did that at school and know how to use it, but there is an easier way" ;)
Quote from: BruceM on November 11, 2009, 11:27:05 AM
You can order the PCBs from expresspcb.com with the file I can send you. It's $53/3. I don't have any.
You guys probably know about printing the layout onto glossy paper with a laser printer and transferring it with an iron on to copper board before etching ??? (heat toner transfer) Saves all the hassles with Pos20 and UV light and such.
http://www.instructables.com/id/5pcb/
dubbleUJay
WJ, I just want to make sure you understand that one processor will be dedicated to the RMS voltage computation. You'll have to interface (serial data) that to another processor which is doing the monitoring and logging. The alternate approach of building your own using a tiny transformer and RC filter will give you a good RMS approximation and way less complication, or you can buy and AC voltage to DC level sensor.
With the advent of cheap PCB fabrication for prototypes (no silk screen or solder mask), I wouldn't recommend etching and drilling, old school. As you suggest, use the better tool.
The use of DC-DC converters around analog circuits where you were hoping for accuracy is perilous for the novice. You will be less frustrated using a linear supply, unless you understand well what you're doing EMC-wise.
Hi Bruce, no I'm not going to have a dedicated processor for the RMS, what I meant is that this probe should be good enough to do it if the Cornell guys used it in there application. I should have been more clear on that, sorry.
The way the guy from FreeEnergyMonitor is using it, he can read the Volts, Amps & Freq with it by using only 2 analog inputs on the processor. From those figures he then gets the power computations.
I don't know of a commercial sensor that can interface all 3 values to a micro with just 2 A-log inputs.
On the other hand, the Arduino board supports I2C which I might find a commercial sensor using that to the board, I don't know.
About the PCB's, over here we pay an arm and a leg for them and the min. quantities are ridicules! We have a "new guy in town" that does smaller quantities, I still need to check him out. In the meantime "old School"is my only option. :'( The same goes for availability of electronic components, it seems that I have to import those HDPL-7520 IC's from you guys, no one has them here in ZA.
On the subject of buying/selling, I cannot sell something on eBay from here, our Reserve Bank rules don't allow for it! It just P-ses me off!
dubbleUJay
Quote from: Jens on November 11, 2009, 09:02:44 PM
Could you explain a bit more on this? What is the reason behind that? How does the reserve bank come into the picture of a private transaction? How can they stop an ebay transaction? What is different about buying something from ebay vs buying from any other place out of the country? Very curious .....
Jens
Jens, they somehow have legislation to stop the local banks from receiving money from PayPal for there customers!
Bottom line, seems they are afraid I might bring money into the country and not give them "their" share of things!
Here's some people asking them the questions:
http://imod.co.za/2008/02/13/i-called-paypalcom-today-from-south-africa-and-asked-wasssup/
and here:
http://www.greenman.co.za/blog/?p=45
I can have a credit card and pay PayPal with it, but I cannot get PayPal to transfer money into my bank account!
People here have sailed around it by having an overseas banking account, but you need a physical address outside my country to be able to open one.
There's other ways to kill the cat, but I'm still just p!$$ed about it!
WJ, In looking at the "open project" page, I see that the project was stopped when the developer noted that his isolation op amps were frying. Excessive differential voltage is what I'd look for. Classic internet project- posted something that did not actually work, another triumph of form over function.
Regarding the Cornell project which developed the circuit you are copying- note that their software is sampling every 1ms (only 8 samples per half wave), and had to avoid floating point calculations in the fast loop, (not the 1 second calc and report loop) because the processor couldn't do it fast enough.
So there isn't much hope for running engine controller/monitor software while simultaneously running RMS voltage and current calculation software.
Processors are cheap, and it makes software much less complex to just add another processor for engine control.
Best Wishes,
Bruce
Bruce, maybe I should rethink this thing a bit ???
Right now I'm wanting/needing a Data Acquisition Unit. I want to measure:
4x Temperatures:
1x Coolant Temp
1x LP Fuel Line Temp (Between my coil around exhaust & Fuel Pump)
1x HP Fuel Line Temp (WVO)
1x Exhaust Temp
on engine side:
RPM
Oil Pressure/flow (Maybe!!!)
Alternator:
Volts 220Vac
Amps 15Aac
Frequency 40-60hz
From those I should be able to cover most of my engine's monitoring.
Now while I'm busy with those, I might as well incorporate some emergency shutdown output if things go outside there parameters and also an output to the assisting governor solenoid we spoke about in another thread, operating if the RPM goes below/above a certain value. I'm not going to worry about real RMS for now.
Maybe also an output to cut out the load if it draws to much current.
From what I've seen/read, these should be easy to implement and shouldn't need to much computing power for now.
I'm now just looking at getting all my "probes" in a row ;)
I know its nowhere near an auto engine controller, but those are the things I'm looking at right now to get working and if I can accomplish that, I would be happy and everything there after would be a bonus, to me anyway. (Then there's the UI on a PC thing as well, but I'll get to that when I'm more or less happy with the hardware)
What are your valuable and very much appreciated thoughts on this Bruce?
Maybe I should change the heading of this thread to:
"Planning a DIY Data Acquisition/Engine Controller Monitoring" for now! ::)
dubbleUJay
PS- Just for interest sake, can a thread's heading be changed?
WJ,
If you're just looking for analog data recording and analysis, a packaged hardware and software system to do just exactly that seems like a huge timesaver, though likely a bunch more money. (Not valuing your time.)
Because I could do the software, I'd design a uP engine controller with the extra analog inputs you need for your research data , and then squirt the data to a PC (if connected) once per second via 9600 baud RS232 or other serial link. The engine controller would continue to be valuable, operationally, all the time you are not doing research (a small part of the time).
I would not mess with developing my own AC voltage and current monitoring sensors unless I had to, and if forced to, then I'd keep it simple (not embedded uP).
Bruce, I think we're on the same "wavelength" now, its just that I'm starting on the opposite side of things than what your suggesting.
This is purely because I need to log data now and the controller side can wait a while.
I'm probably going the wrong way around as the Engine controller would be the main program and the Data Logging secondary, but on the other hand, I'm a south-paw ;)
I presume the code for a data logger that I have now would easily be adaptable later into a final system ???
BTW, the guy on the FreeEnergyMonitor site has just changed over to use a CT method for measurement of the AC 'cos of the problems he was having with the IC's blowing.
My guess is that the Cornell guys were pushing the design with 110Vac and he changed it to 220Vac, from there his problems. It's probably high frequency spikes that caused the faulures as they also didnt incorporate any filtering as suggested in the App-notes of the components.
I'll probably use a diode to cut out the negative going pulses to the IC's and rework the formulas from there IF I'm going to go this way, do you know of a commercial probe that will read the Volt/Amp/Freq all in one that you will use then?
dubbleUJay
I haven't found a power monitoring sensor with amps, freq, and voltage all in one. I can see the appeal of the Arduino based design for your application, and if you can get it to work reliably, you can just add another Arduino for engine control and monitoring.
In looking at your own modified circuit diagram, I see some serious problems, and have questions.
Your AC is 220, but I don't see a neutral identified, and instead see three hot legs. None of which seems to be tied to any DC ground for reference. This is a guaranteed smoke maker.
If one of the legs is neutral then that can be tied to the DC ground of the iso-opamp input side as was done in the Cornell circuit. This circuit would then not really measure the 220VAC, but only one leg as shown if the DC supply is tied to the neutral. But that would then work as per the Cornell schematic, and might do the job for you. You'd just need to double the voltage in the calculations. This will NOT be accurate for a generator configured as 220VAC with a neutral, with unbalanced 120VAC loading. For a 220/240VAC generator head setup as L1, L2, Neutral, you'd have to use two 120V devices.
For a genhead producing only balanced 220/240AC the DC ground could be tied to one of the hot legs, then the device would see the the full differential between both hot legs.
Either way, you can't have the measuring op amp floating relative to what's being measured.
The iso-op amp outputs also appear to be mislabeled in your drawing. You have shown the op amp pin 6 as an output, but it is a voltage reference input. The capacitors directly attached to the output pin without a preceding resistor may be a problem, check the datasheet. Adding capacitance directly to an op amp's output is a bad thing, and often causes instability. If you were trying to filter the output, a 1K ohm resistor in series is needed.
As I mentioned earlier, the use of a switching DC-DC regulator as shown will destroy your accuracy. If you look at the spec for ripple on the regulator, you'll see what I mean.
For a dedicated voltage, current, and frequency meter, I don't like the isolated op amp design by the two Cornell students. It's cheaper, simpler and more accurate to use an opto-isolated serial link from microprocessor to the host computer. This solves the isolation problem and keeps the processor/analog board much simpler. Only a single linear 5V supply would then be needed.
The jar meter which was the predecessor to the Cornell project is a better design, IMHO. You could steal their hardware design but still use the Arduino board (though you'd have to loose the USB since you'd need opto isolated serial.
Bruce, I labeled the AC supply legs, forgot to do that with Eagle, the component library didn't allow me to change the pin names so I had to delete them and make separate labels, sorry for the confusion. (Modified cct diagram attached at the end of post)
In ZA our Neutral and Earth is effectively connected together at the utility supply point, not that I'm reading the utility supply, but something I've got to keep in mind for the future.
I saw in the AppNotes for the 7520's that the input GND1 & VIN- are connected together, but not in the cct of Cornell ??? The same goes for the modified cct from the FEM site.
This is a bit confusing for me as I don't see how they "reference" it!
Pin6 of the IC's are Vref, again, sorry for that, Eagle didn't have a component schematic for 7520 and I chose one that I thought was the same, didn't see that pin :-[
I should stop drawing these late at night/early morning ;)
I see your point about the DC-DC, just shows you what experience is all about and why you are the moderator here 8)
Now my question: If I use a surface mount isolated step-down transformer (220-9) rectified and filtered, but powered from the generator head, would that be OK?
I'm worried about the voltage and frequency on start-up/shutdown not being nominal, would that matter?
Thanks Bruce,
dubbleUJay
PS- I left the DC-DC on the cct for now, will change it if you think the transformer would be OK
WJ, I just checked on an Avago design note for your HCPL-7520. It shows the input side chip ground being connected to the power (neutral). The device is not capable of floating measurement as your diagram shows now.
I did check both of the schematics- Cornell's and the other guys. They both don't show the connection of neutral to the 5V ground. It's just a goof on Cornell's schematic that got copied by the next guy. This is the problem with much of the stuff on the web. It's not your fault for copying their mistake.
Your placement of capacitors is not right, get rid of them. You shouldn't put them on the outputs without a resistor first, and you shouldn't put capacitors directly across the inputs of the op amp. Put a resistor between. This is basic op amp stuff you're just forgotten.
The second 5v power could come from the Arduino board...it's very low power.
Bruce, I'm getting confused now or I'm confusing myself! (Which happens a lot lately) ;)
Attached are 2 pages from the AppNotes from Farnell for this IC.
I more or less copied the caps from that cct for protection. It did look like a non-conventional way of doing it, but who was I to point it out if Farnell had it in their notes. They have the GND1 and Vin- correctly connected BTW as you rightly pointed out.
Its been 10 years since I last put something like this together, cct's I build recently didn't need any "thinking work" as they were just duplicated from existing stuff!
2ndly, about the power, my one 5v is coming from the Arduino board, I just wanted to know if you see any problem in generating the 2nd 5v from the actual generator head with the frequency and volts increasing and decreasing on start-up and shutdown of the engine until operating speed or standstill is reached?
Hope I'm not testing your patients!
dubbleUJay
The circuits you show are from a switching motor drive circuit, which adds some confusion. But in both cases, you will see that the 5V ground is in fact connected to the motor drive negative. In your circuit, the 5V ground needs to connect to neutral.
The capacitors all over the Farnell circuit are an attempt to cope with the massive noise generated by such high power switching. These types of motor drives are notoriously glitchy, generating great transients and some impressive EMI. If we believe the published circuit, (many are incorrect) then the device is stable for such capacitance on inputs and outputs. (I haven't studied the part in that great of a detail in the manufacturer's data.) You're not likely to need them.
OK, thanks Bruce, from what I've gathered now, I think I can should build a prototype. I tried to order some of the IC's and I'm still waiting for the suppliers to come back to me. If I don't come right this coming week, I'll have to get them from the UK or USA.
I've managed to get an interim software solution going in the meantime.
As previously posted, I got the Inbetweno software going which just write time stamped data from the micro to a file on PC. From there I can pretty much do what I want with it.
I've been using LM35(LM34 for F) as temperature sensors, but I'm also waiting for some Dallas 1-wire temp chips which will only occupy 1 analog input and leave the rest of the pins for other things.
The KST graph program is a bit unstable on my PC, so I tried to link M$ Excel to the data logging file from a 30min run of my engine and this is what I got: (The reading does not make a lot of sense as I moved the probes around on the engine while running the test, but you get the basic idea)
On the GREEN plot one can clearly see where I changed back from WVO to Diesel as the diesel does not go through the loop around the exhaust to heat it and the temperature dropped.
I'll post some pictures on how I made the probes when I get a chance.
Nice temperature plots, WJ.
WJ is using a compiler on the AVR based Arduino board, Jens, but even the Picaxe basic supports (via ow commands) one wire sensors, but I wouldn't use one wire parts as they are incredibly slow. (The parts, not the code.) LM34/35 are what I use.
WJ,
If you need to add analog ports, there are I2C or SPI bus parts to do that directly, or you can use a cmos analog multiplexer (74HC4067) and get 16 channels on one A/D input, though that needs 4 digital outputs to address it. An I2C 16 bit digital I/O chip like the MCP14067B might round things out to provide some extra I/O. SPI is typically faster, but I've used and like I2C for my typically modest speed controller applications.
Jens, this is what I like about this board, most have been done: (Although with a library and digitally, not analog pin as I incorrectly stated,sorry)
http://www.milesburton.com/index.php?title=Dallas_Temperature_Control_Library
and here
http://www.phanderson.com/arduino/ds18b20_1.html
I figured that timing would be an issue, but I'm not there yet, once I put all the code together yes!
Quote from: BruceM on November 14, 2009, 08:23:33 PM
Nice temperature plots, WJ.
.....
WJ,
If you need to add analog ports, there are I2C or SPI bus parts to do that directly, or you can use a cmos analog multiplexer (74HC4067) and get 16 channels on one A/D input, though that needs 4 digital outputs to address it. An I2C 16 bit digital I/O chip like the MCP14067B might round things out to provide some extra I/O. SPI is typically faster, but I've used and like I2C for my typically modest speed controller applications.
Thanks Bruce.
I did see somewhere how to increase the analog inputs of the Arduino, maybe I should look at that, thanks.
The 34/35 are known good working sensors. The remaining Analog pin can then be used for things like oil pressure exec. in the future, as long as I then don't run out of digital pins once I start needing then for control! ???
I'll hate to get near the end of the project and than have to change everything around again! :'(
PS- and what I know about I2C at this stage is that "I to see" problems for myself in the future ;)
Here's some data I found for you WJ:
Table 1. DS18B20 Conversion Times and Resolution Settings
Resolution 9 bit 10 bit 11 bit 12 bit
Conversion Time (ms) 93.75 187.5 375 750
LSB (°C) 0.5 0.25 0.125 0.0625
You can now see why I don't like the 1 wire sensors for some applications. If the software is written cleverly, this is not as bad as it seems, but with library routines you'd best take a close look or write some test routines to see how much of the latency turns into program execution time wasted. Note the 187 ms for 10 bit, 750ms (!) for 12 bit. If you read 4 of these even at 10 bit resolution, that's 0.75 seconds just for the temperature reads.
The generator power output relay should not trip closed until voltage is up to snuff. This way your equipment won't see a slowly rising AC voltage. There are nice monitoring relays that do this, or you can make a simple one with a resistor to raise the turn on voltage of the relay a bit.
Best Wishes,
Bruce
Thanks for the more detailed explanation on latency, Jens. I got lazy.
The trouble with dealing with the one wire latency for novice programmers is that they can't cope with the extra real time sequencing and complexity, so the slightly greater ease of wiring (cost is insignificant in a single unit) becomes the pain of software headaches. That's not a good bargain.
Quote from: BruceM on November 14, 2009, 11:58:51 PM
Here's some data I found for you WJ:
........................
The generator power output relay should not trip closed until voltage is up to snuff...................
Bruce
Thanks Bruce, since this mornin' and your last post, I've been reading some more about the 1-w sensors and using the multiplexer you've suggested.
Jens, I can "see" what you're saying as well, almost like using the temp reading routine as a 2ndary loop somewhere, coming back to it every time.
I've more or less decided to use an extended analog input board like Bruce suggested, I looked at the 4067 (x16) and the 4051 (x8). It seems that the 4067 would be the easiest, less components and both can easily be extended for more channels.
This will mean that most of my sensors will be analog (or use DAC's), but that is what my sensors are at the moment anyway. As said previously, I hope I don't run out of Digital Outputs in the future, but there's probably a way around that as well, but the Arduino has 14 Digital I/O's, I'll use 4 for the extension board, 10 should be enough I think for control. (That's if I don't find something else that need digital BTW)
If I want to in the future, I can probably go ape with all the sensors I can connect, monitoring Wind, Solar or whatever, just depends on my sensors. If this V/A sensor works, it can be adapted to read almost anything with ease.
Your 2nd thought Bruce, I was thinking to mount the V/A sensor in my gen-head, so the supply for the 2nd 5v would be directly connected to the output, not via the load relay, but I'll be using a 5V Regulator between transformer and IC's anyway, so I don't think it would have problems.
It would have been nice though to have some sort of independent supply for it if I need it in the future again for the same type of sensor.
Some idea just struck me (Were is the light bulb smiley when you need it ;D ) are these switch-mode AT(X) PC power supplies isolated from the mains?
Its way overkill, but can I use two of them to have 2x isolated 5Vdc rails, I've got enough of them lying around anyway and the 12V (or +12-0-12- = 24V per PSU, not using both to make 24V) can do my relay and contactor switching and probably some battery charging to a certain extend ???
I've got to put this in my pipe and smoke it for a while, but do you guys think it will work?
dubbleUJay
Thanks Jens, I should know about the charger side! :'(
I was thinking to justify using such PSU's for just 2x 5V rails, clearly not thinking straight!
Anyway, yes, the negative is common to all the voltages, its easy to make a mistake.
Maybe I'll just have to get a transformer with 2x separate 9or12v secondaries and built an isolated power supply.
It's just that I'll sit with the same problem in the future when I want to read a wind charger, battery bank, solar panels and/or DC alternator.
I'm planning a 24v system as my gen-head's build-in starter is 24v and gets used as a DC charger as well, so I'm going to stick to 24Vdc.
Those small DC-DC board mount converters would have been ideal if they were to work, but apparently not. :(
Bruce, are there ANY change a 5to9Vdc inverter might work with proper filtering on the output and a 5v Regulator before going to the IC's?
I don't want to squeeze blood out of a stone, but can you see my point if they were to work? Obviously I wont use the USB to power all the external circuitry, but the ample 5v supply on a AT PSU.
Jens, do you care to give a comment on this as well maybe ???
Again guys, thanks for all the help and patients :-[
It's a lot easier for a novice in electronics to get clean, analog accuracy using small linear supplies. With SMPS it's much more of a project. Tiny PCB transformers (you need very little power) are cheap, then all you need is a tiny bridge diode dip, electrolytic capacitor, 7805 and a couple 0.1 uF caps. Why make it hard for yourself?
If your later engine monitor/control is going to be 12V battery operated, this might also affect how you do your power scheme.
If you were to draw a diagram of your system, showing what gets powered from where, including the data logging computer, I can probably save you some trouble. I don't think you need the isolaton amplifiers.
OK Bruce, I'll have to draw it in the morning, I'm busy falling asleep this side and it only 19h00!
And then the wife tells me it's not work sitting in front of the PC the whole day, how can I be tired! :P
Talk soon,
Wilhelm
"Well, I have no experience with DC-DC converters but I don't understand why there would be an issue using them."
That's a common misconception.
Switchers have considerable ripple voltage and generate EMI on the power and grounds which can cause gremlins and frustrations in designs without proper ground and power distribution, filtering and design. This is particularly important in circuits with both analog and digital. It is of less concern for digital circuits which are more tolerant.
It is easier to suggest to a novice to avoid them (SMPS or DC-DC converters) than to try and teach them how to use them. This is the electrical engineering field of Electromagnetic Compatibility or EMC, and there are plenty of good books on the subject. With linear supplies, as long as the circuit is wired properly it will work pretty well, even if layout and design is primative.
Keeping things simple makes prototypes or "one of a kind" projects more fun.
In WJ's situation, I suspect his whole setup could be run off a single 12V supply (later to become his 12V battery), with no isolation. His ZA 220VAC has a neutral and one hot leg, plus safety ground. If his generator has one leg tied to the neutral, then he has a common neutral/DC ground and isolation isn't necessary.
A simpler, non-isolated design for voltage and current sensing is at:
http://enerjar.net/
Ok guys, here goes, I hope the diagram makes sense.
As you can see from the drawing, stuff works a bit different here, I think they followed the Brit setup years ago. (More or less)
I'm still considering connecting my Neutral to Earth on the gen-head like the utility does. We don't like floating voltages around here ;) One more thing I should mention, a lot of our household appliances are wired wrong, (Not mine, but I see it all over at other places) ie the L & N switched around. This does not make a difference in the operation of the appliances though. (Or most of them anyway, some control gear, like my well pump does not work as it checks for the correct polarity to earth)
Also, I have not implement a battery bank yet, still waiting for the right deal ;) I just have 2x automotive batteries for starting and operating the controlling gear.
Everything will be 24V, so 12V or 5V will have to be regulated.
Although I have a few PC UPS's that run some stuff, mainly just for the change-over time until I start the generator.
I didn't draw the transfer switching gear as well.
O-yes, I should mention that I have a few solar panels and a wind generator in progress, so from there the ability to monitor them as well in the future.
Thanks,
dubbleUJay
That helps a lot, WJ. It looks like you're going to need a transfer switch before your main distribution panel, if you plan on powering the house with the generator. But it's easy, as you only need to switch the single hot leg. Yes, you should bond the 24VDC ground to the genhead neutral, yes, a local ground rod at the generator is a good idea, and you'll get a gold star if you bring that ground back to the distribution panel ground.
Now you should decide about the engine controller/data collector. If it's to be autonomous of utility power for engine operations, and I think it should be, then you will want to run a tiny 24 to 5 volt converter, with some extra LC filtering on both ends. It could be a buck converter (most efficient and simple) if you don't need isolation, and I don't see why you would. My generator shed is 12V, so I don't buck, just down (linear) regulate. The power consumption is very low (50 ma or less).
For hand built work with switching supplies, find some copper foil with adhesive to make ground planes with. I will often lay out a full ground plane, then cut away for parts, etc. I also often use copper tape strips on the other side for power distribution, before I put in the point to point wiring. 0.1uf ceramic caps at each component, to the ground plane. This will get rid of most of the glitchies.
Quote from: BruceM on November 16, 2009, 01:57:53 AM
That helps a lot, WJ. It looks like you're going to need a transfer switch before your main distribution panel, if you plan on powering the house with the generator. But it's easy, as you only need to switch the single hot leg. Yes, you should bond the 24VDC ground to the genhead neutral, yes, a local ground rod at the generator is a good idea, and you'll get a gold star if you bring that ground back to the distribution panel ground.
OK Bruce, at the moment I'm using a very dangerous way of transferring the power with a multi-change-over contacted relay. When the utility falls away, the relay releases and connects the generator to the house. Obviously dangerous if the contacts should arc or bridge for some reason and the utility & generator runs at the same time. I'm in the process of getting 2 interlocking 3-pole contactors rated at 60Amps, the ones where only one of the two can be operated at a time. We don't have strict rules here or more correctly, they are not enforced, but I must still make it safe for myself and the utility workers.
I'll rather switch all three legs (L-N-E) as one never knows when a tree blows over on the poles and shorts out some supply leads exec.
All my power cables I run are 3 conductor armored cable in-between the various boards, so yes, my earth is connected all over.
I learned all this when I use to work at a Telco company, building outstations like microwave towers exec. We had to incorporate lightning divertors as well, so I believe in earthing everything possible! ;)
The only thing about the Telco stuff, all the positive battery terminals were earthed to ground, the opposite way around than the norm, apparently to do with rust in an airconditioned room, but I just took their word for it, 'cos I couldn't run tests ;)
Quote
Now you should decide about the engine controller/data collector. If it's to autonomous of utility power for engine operations, and I think it should be, then you will want to run a tiny 24 to 5 volt converter, with some extra LC filtering on both ends. It could be a buck converter (most efficient and simple) if you don't need isolation, and I don't see why you would. My generator shed is 12V, so I don't buck, just down (linear) regulate. The power consumption is very low (50 ma or less).
OK, I've understand that. The controller and for that matter all relays and contactors will/must run off the 24Vdc controller/starter battery which will be charged by the 5Amp DC generator charger and probably a trickle charger from the mains. This is all separate from my planned 24V storage batteries which will be charged with wind, solar and UPS charger.
Quote
For hand built work with switching supplies, find some copper foil with adhesive to make ground planes with. I will often lay out a full ground plane, then cut away for parts, etc. I also often use copper tape strips on the other side for power distribution, before I put in the point to point wiring. 0.1uf ceramic caps at each component, to the ground plane. This will get rid of most of the glitchies.
I'll probably use strip-board (Vero-board ??) to build it. I found an article somewhere that reminded me of all the 5to9Vdc inverters on those old PC network cards, the 10base-T ones with RG-59 connector. They look quite robust and I'll try one of them 1st. The plan is to use a 5v reg on the output. I'll see how using ground planes underneath it will work.
I looked at the network cards and they are heavily "planed" top and bottom, probably all the sandwiched layers in-between as well!
I'm just a bit worried about the Arduino using the USB power to power it from PC when you connect it for monitoring! I'll have to wrap my head around that a bit more.
Thanks Bruce.
PS- I'm just about ready to build the analog multiplexer extender board with the 4067 you suggested, I'll probably run the cct past you this afternoon just to check before I build if you don't mind ??
Bruce, look what I found now:
http://interface.khm.de/index.php/lab/sensoraktor-shield/introducing-the-board/
It does a lot of interfacing to the Arduino board.
Pity there are still only 6 analog inputs, but I'm sure that can be extended.
I've emailed the guy to hear about availability and cost, it would be so much easier for anyone to just buy the stuff, at an affordable price obviously.
This will add stepper motor control as well.
What do you think ???
Good morning WJ,
I don't see much appealing about the board- unless you need the small motor driver or something else.
"all relays and contactors will/must run off the 24Vdc controller/starter battery"
Some could be 220VAC coil, with a small DC relay to control- this can take a load off of your 24VDC, and reduces the power requirement for your interface board's drivers (logic level mosfets with 1K ohm to gate from your DOs; switch the low voltage leg with N-CH mosfets).
Switching the Neutral and Earth between your mains and genshed is not a good idea, they should be bonded. Then you can never have a surprise. Do you know if your power co. distribution lines are Wye (neutral jumped around transformer) or Delta (both distribution lines hot, the neutral derived at the customer side of the transformer)?
You need to show how your PC is going to be powered, and this gets back to genshed neutral. It really should be permanently connected or you will have to do some isolation.
Best Wishes
Bruce M
Mornin' Bruce, the time difference between us are about 8 hours I think, its 04h00 over here, busy with my 1st cup of coffee!
About the SensorAktor board, I meant that some of the cct's could be used. I'm sure somewhere in the future I'm going to try your stepper motor throttle. I was thinking that while I'm going to have to build an extension board for the extra analog inputs, I might as well put more things I will use on it and maybe a floating isolated 5v supply for the VA sensors as well if I'm going that way.
The guy that made the board are a student at a "media school" and the board are not commercially available. He has offered to send me the Eagle files which will save me a lot of work. I'm thinking of taking the stuff off I wont need like the pot, mic input, exec., and putting the multiplexer onto it.
I'm probably thinking to far ahead without actually building a prototype, but I think most of the work in such a project goes into the planning of it. The making of the board will be quick, but I'll hate to find out in a months time that I have to build another one because I left out a motor driver chip.
Don't get me wrong, it will happen, but maybe to a lesser extend if I "TRY" and think about most of the stuff now. ;) I'm now waiting for him to send me the Eagle files and will take it from there.
O-yes, one more thing about his stuff, he also developed a multiplexer board, using scalable CD4051 (8ch) for up to 24ch's. There are more components involved, but what I like is that he uses 3x digital outputs to address it and not 4 like with the 4067.
This means that I might do away with the 3 outputs on the SensorAktor board and run the multiplexer from there without interfering with the rest of the design.
Anyway, this is all still up in the air, I need to get the VA sensor going. ;)
I'm not sure which type of step-down transformer the utility use, but here is a picture of it. We can apply for 3-phase power and the poles down the road have 3-phase Live & Neutral on them. The phases gets distributed evenly between the dwellings around here. We have 220V between Neutral and any one Live phase or 480V between any 2 phases. The carrier voltage is probably a few thousand volts on the poles I presume, I'm not sure if they stepped it down before entering the area.
Looking at the picture, it seems they either have 2 phases to the Xformer or 1-phase and Neutral, but its probably the Delta configuration you asked about.
The PC is powered via a UPS, but to be safe, I would like to presume that it will be powered from the mains. I don't want to get any surprises if I do plug it into the utility mains one day! ;)
Have a great day,
dubbleUJay
PS- I know what you said about others not want to build or acquire stuff like this, but I'm still leaning towards making it possible to do so. If I/we make this project available here and people see that it works or see what others are doing with it, maybe they will get one ???
If someone like yourself can get a few extender boards made for the guys in the US in the future, that might be a great incentive for them. I'll have all the cct & PCB layouts in Eagle ready for anyone to download.
It might just be a matter of getting an Arduino, Extension Board, a few sensors, download the UI and Bob's your uncle!
I suppose it all depends on the stuff one can do with it and the user interface on the PC.
Maybe I should take a poll on the forum and see who might be interested in such a thing, givin' the criteria above ???
Don't get me wrong, I don't want to make $$ out of this, I actually want to stick it to the commercial products available out there that's ridiculously over priced! :(
Your secondary distribution line is odd- you have two hot legs and a neutral, apparently. It's unclear what they're doing without a wiring diagram, but it's probably Wye. Power co's do things differently the world around, many times (like Wye grounding practice), a knowledgeable EE will be in horror.
I'm sure if you make a nice expansion board for the Arduino that some folks will be glad for it.
The time involved is significant- I just spent the last week getting my PCB artwork and documentation up to snuff for my battery bank charge controller. (Two boards.) My God, I can't believe how many days work on it!
Quote from: BruceM on November 17, 2009, 12:07:07 AM
The time involved is significant- I just spent the last week getting my PCB artwork and documentation up to snuff for my battery bank charge controller. (Two boards.) My God, I can't believe how many days work on it!
I'm lucky in that sense that I have a lot of time on my hand when I'm not running the financial side of this machine of ours in the picture!
The Tadano mobile crane that is, not the yacht :'(
WJ- I forgot to respond to your suggestion of cleaning up the switching regulator output by linear regulation. Yes, that would work in reducing ripple. You'll need maybe 4 volts above the regulated voltage, less if you can live with the regulation of an LDO regulator (not as clean an output).
Hi Bruce, the 5to9v inverter with a 78L05 should work nicely then I presume. I will still apply the suggested filter caps from the app notes and see what the output looks like.
That reminds me to borrow my friend's scope! ;)
I'm STILL waiting for an answer from my supplier about the HCPL-7520, he told me today I should know by tomorrow afternoon. If they aren't available here, the whole VA sensor might fall flat and I'll have to try some of the other suggestions discussed previously in this thread.
Couple projects you might find interesting:
Edward Cheung's HA Power Monitor Node (http://www.edcheung.com/automa/power.htm)
I've been fascinated by this guys work for years. PIC software, schematic, and info about his DIY CTs provided.
And my own small foray into CTs, though I haven't done anything with it yet.
Whole-house power monitoring, need op-amp help (http://www.appdigusers.com/forums/ubbthreads.php/ubb/showflat/Number/20576#Post20576)
(The Ocelot is a consumer version of an Industrial PLC controller running Ladder Logic programing, for Home Automation / SECU-16 is an I/O expansion module for the Ocelot)
Great stuff to get ideas from ndavid, thanks! I've got some reading to do. ;)
Well guys, I've been sidetracked a bit with the fuel-flow meter while I was waiting for the electronic components to arrive for this project and I'm STILL waiting!
Well, sort of sidetracked, as my intention is to incorporate that meter into this project, but I didn't want to put it in this thread as it's already getting pretty long.
I got most of the goodies, but the IC's for the Volt/Amp probe I cannot find stock for in ZA, although I might have a change with the manufacturer of the IC as I've written them a motivation for some samples. (Yeh right! ;-)
Importing is now out of the question due to cost, just to give an example:
CD4067 16ch multiplexer $0.62
CD4053 8ch multiplexer $0.28
74HC595 shift register $0.36
and then the HCPL-7520 at a whopping $21.08 !!!!!!!!!!
OK, I know its not a very good to compare between digital and analog IC, but still, I cant afford 2 of those for a developing project were I'm probably going to blow them up as Murphy would have it!
NOW, Bruce my main man!! (Some more flattering follows.... and more.... and some more ;) )
How "safe" would direct coupling be with resistors for the 220Vac voltage with maybe a AtoD converter with a 0-5Vdc scale and the same goes for reading the AC amps up to about 20Aac for my application anyway?
I priced 0-5V output Current Transformers and they cost a fortune as well by us! :'(
I might consider turning my own or use an universal one (in my spare parts box), but then I need the circuitry to give me the correct output and also calibrate it.
Also, I need to either get the mains frequency from one of these two inputs or use a separate A-in pin for it.
The reason I "clinged" so much to the opto-cct is that I thought it might work in the other applications as well with minor resistor changes, but that's probably out the window now. :'(
One more question, I reconsidered using the 16x multiplexer (4067) you suggested and I'm going to use that to extend the analog inputs. The ATmega328 has 6x digital and 6x digital (PWM) outputs on the Arduino board. Would you use the "just digital", digital PWM or a combination of the 2 to control the 4067?
It might sound like a stupid question, but the pins are mixed and all over the place, ie pins 2,4,7,8,12,13 are just digital & pins 3,5,6,9,10,11 are PWM. I would think using 4x pins in a row will make programming easier, but I don't want to run out of PWM's in the future as well ???
Anything I'm missing that you guys maybe see, please let me know.
Thanks,
dubbleUJay
WJ, As I suggested before, there is no need to use those pricey isolation op amps. The same design will work without them, if you are able to understand it well enough to adapt it.
If you want isolation, so that you can measure without having to tie your genset neutral to the mains neutral, then you need a tiny transformer with a fairly high output. If you can live without the isolation, it's more hazardous to the experimenter, but you can just scale the half wave rectified AC with a resistor divider scaled so that your highest (max high voltage peak) AC voltage is just under 5V. The zero cross can be used as an input to clock for frequency counting, and for syncing RMS sampling. (I'm not familiar with the AVR chip.) The zero cross is most accurate with a higher voltage input such that diode loss near zero is insignificant.
I would not bother with real time waveform sampling and RMS calculation. Why tie up the processor for a simple analog job. I'd just integrate the half wave AC voltage with a capacitor, and buffer it with an op amp voltage follower. The range can be rescaled by op amp to give you better AC resolution, if you want to. I have a circuit that converts 110 to 160VDC to 0 to 5V for your reference. Pick an available RR micropower op amp. You can then just read the voltage direct to an AD. Just make sure to calibrate well using a variac and good AC voltmeter or other means.
For current, you can do essentially the same circuit (half wave rectify and filter to DC), but feed it with the output of a homemade CCT.
Again, if you want to run their software and dedicate and AVR to do it, you can also still use the same setup as the Cornell version, but without isolation.
Regarding the analog multiplexer, you will have to use 4 output bits and yes, they should be assigned to 4 bits in sequence, preferably the low order bits of some output byte.
The PWM outputs would be of use for some analog control...and usually it will be to use them for RC servo control. I can't imagine more than a couple.
Thanks Bruce, I'll have to read it a few time over, just have to go and fix well pump for someone quickly, no water!!
Bruce, may I run this cct past you for the 16x analog extender with the 4067 before I build please?
From a designers point of view, would it be better to keep the unused/open pins on the IC to Gnd or 5V and would a 100k be OK?
Sorry for the ignorance on my side, give me some relays, motor uni-selectors exec. and I'll build you an electro-mechanical switch board, but my electronics are very rusty as I'm finding out now!
I must still change the controlling inputs from the AVR to run in sequence as you said before, will do that soon.
Thanks in advance,
dubbleUJay
WJ
It's fine to leave unused analog inputs open, just don't read those addresses. If you want to read them, then pull up or down, but 100K is stingy, check your board for required input impedance. 10K is certainly safe.
Got my PCB back for my battery bank charge controller. No fatal flaws, just one chip width error, on the 74HCT4067. An adapter will bail me out. Finished the first pass design and PCB layout for my big 120V 10A linear regulator. You should see the heatsink- 12x9, 1" fins. (300 watts dissipation, peak). I'm going to be very busy for a while!
Thank Bruce, answers lead to more questions ???
I was thinking of making the code universal, ie reading all the pins at 1st and if there's problems with timing and such when the rest of the code gets incorporated for other things, just leave the unused ones out. (IF there is problems)
10k resistors won't influence the reading significantly of analog pins if they are present/"left in" on a working pin to ground would they?
Another thing I found while reading the board specs as you suggested, are that the A-pin 4&5 can be used for I2C bus, I'll leave those alone for now as well, might need them in the future. ;)
I'm glad you got your board back, its a pain waiting for stuff so that one can continue, ask me! ::)
Pity about the chip error, could you not get the specific package or was it just a fault that crept in along the way?
I've got a similar heat-sink for just such a application, although its 6x6, but 3" fins! Came out of a 3kVA inverter, so it should be ample!
dubbleUJay
FYI Bruce, I previously spoke to you elsewhere about my brother being in Ireland, well he's back now after calling it a "day" after 6 years!
He's use to livin' in town, but now he has moved into a place close to me.
All of a sudden he has to look after/dispense of his own $h!t, literally and figuratively! We've got no water or any municipal services around here. One has to make do by yourself and obviously "big-brother" has been doin' it for about 8 years, so now he wants power backup, running borehole water, exec. and guess who has to help! ;)
Anyway, all in good time!
Talk soon and don't forget to update your thread on the regulator your building! ;-)
"10k resistors won't influence the reading significantly of analog pins if they are present/"left in" on a working pin to ground would they?"
You shouldn't leave these in- perhaps you can just put pull down resistors on the unused connectors. Or use a dip header and resister carrier/dip which can be removed. Or just a place to solder them in but cut away when assigning the channel.
I just assumed that a 74HCT4067 24 pin package would be 300mil spacing- but it was the old style 600mil. Not fatal, there are adapters. It cost me just $112 for the circuit board (2) delivered from expresspcb, a bit rework is nothing compared to hand wiring that much stuff! I had the board in 4 days.
My big linear/mosfet bypass regulator has limited appeal, not too many folks with 120V battery banks!
Today I will daringly drive out to my remote property shop to get parts, do some soldering and do some work on the AC charger assembly. I've been too ill for that for a long time. It's been very slow recovery from adverse drug reaction (experimental for MS) which caused accute hepatitis, just about finished me off 5 months ago.
Folks vary in adapting to different lifestyles, I hope your brother will find settling in there not too difficult.
Best Wishes,
Bruce
Quote from: BruceM on November 22, 2009, 10:11:59 AM
You shouldn't leave these in- perhaps you can just put pull down resistors on the unused connectors. Or use a dip header and resister carrier/dip which can be removed.
I thought there was more to it than meets the eye, for now I'll put up with the sporadic readings on the "open" channels until I'm more sure which would be used or not.
Quote
I just assumed that a 74HCT4067 24 pin package would be 300mil spacing- but it was the old style 600mil. Not fatal, there are adapters. It cost me just $112 for the circuit board (2) delivered from expresspcb, a bit rework is nothing compared to hand wiring that much stuff! I had the board in 4 days.
The same thing almost happened to me, luckily the 4067 comes in both, but I'm building one "Vero" for now, so it doesn't matter.
My biggest problem in ZA is availability and services. Don't get me wrong, I can get anything done, but its going to cost me if its not a regular item or service!
The only guy I know about in ZA that does PCB's of "acceptable" quality is this bloke:
http://www.cboards.co.za/pcb_sameday.html
He can make single & "double sided" (No through-hole plating :'( ) in small quantities:
100x160mm single at about $29
200x160mm double at about $69
The rest of the blokes want a minimum of 20 and up boards :o at some serious wallet eating prices!!
Quote
My big linear/mosfet bypass regulator has limited appeal, not too many folks with 120V battery banks!
If I knew then when I know now, I would have had a nice set of 220Vdc battery banks! We use to install/replace those big glass jar-type flooded lead-acid batteries at the remote telecoms stations I spoke about previously. They were huge, I forgot the capacity now offhand, but they were standing at least 40" tall! A lot of them got replaced on maintenance schedules and were still OK. Most were wired for 50Vdc.
I dropped a number 13mm ring spanner across the buss-bars once by accident while charging a new set! This was at about 2 in the morning as we had our alarm-clock set to wake up on set times to check charging rates.
Needless to say, I didn't sleep after that and could not find anything left from the spanner but little metal balls all over the floor! That bank ONLY had a 400A fuse, nothing serious! ::) 48Vdc at 400Amps are serious stuff, the buss-bars were copper flat-bar approximately 6x1/2".
I must scratch around for my "analog" pictures one day and scan them. Then there was the time lightning struck the tower we were sleeping in, but that's a story for another day! ;)
Quote
Today I will daringly drive out to my remote property shop to get parts, do some soldering and do some work on the AC charger assembly. I've been too ill for that for a long time. It's been very slow recovery from adverse drug reaction (experimental for MS) which caused acute hepatitis, just about finished me off 5 months ago.
Hope all goes well Bruce, I don't have to say this, but take it easy with the drive!
I got diagnosed with "chronic pancreatitis" about three years ago, no official medication for it so one tries all remedies and sh!t and some of them gives bad side effects as well! Not nice! I now believe they (State Hospital) misdiagnosed me at the time 'cos apparently I would've kicked the bucket by now, but like hell would I go back there now that I'm feeling better! I spent about 1 year in hospital all together for tests, scans exec., before they gave me a diagnose and now it may be wrong!
Medical treatment are REALLY, REALLY BAD in ZA if you don't have medical aid, that's to bottom line!
Quote
Folks vary in adapting to different lifestyles, I hope your brother will find settling in there not too difficult.
I believe its a good thing for people to come back to earth some time!
Around here one sees all the folks which let everyone believe they were so well off, getting hit hard in these world wide economic problems everyone's havin'.
They are crying 'cos they have to give "their" stuff back to the banks. I don't mean essential thing, stuff like flashy cars, Johny the 3rd's Blackberry, exec. ;D
BS, what a farce!!!
Anyway, I talk to much,
dubbleUJay
WJ,
Did you really find a 6067 with 300 mil spacing- give me a part number, please!
Your circuit board situation sucks- no plated holes?! The quality and prices I've been getting from expresspcb is amazing. There are some services in China that perhaps you could use, check the sparkfun.com web site for links.
Bruce
Quote from: BruceM on November 23, 2009, 10:59:12 AM
Did you really find a 6067 with 300 mil spacing- give me a part number, please!
Bruce
You probably meant 4067, the one I'm using for the multiplexer board you suggested I use previously.
I got a HEF4067BP (SOT101-1), the broader one, but there's a HEF4067B by Phillips, which looks like the narrow one on the spec sheet, I might be wrong though.
Then there's also the CD74HC4067 by Texas which seems to come in both packages if I look at the specs.
I just hope we're talking about the same dimensions here ???
About the board making in ZA, I've got a few feelers out to see if I cannot come up with something else, will let you know.
I got the multiplexer going, now just to adapt the code for it, but I'm reading values from it at least.
Hope everything went OK 2day with your traveling, I'm off to bed now, I've got no idea how I'm going to sleep 2night with all this Arduino multiplexer "code" floating in my head ;)
dubbleUJay
That's great that you got your multiplexer going, and thanks for the chip tips, I'll take a look.
Alas, I didn't get away with my trip, a real setback.
PS- no 300mil versions of the multiplexer that I can find from my suppliers. I just bent the first 12 legs out straight and soldered it in as a sip with a 12 wire lean-to.
Fugly!
Quote from: BruceM on November 23, 2009, 02:50:02 PM
That's great that you got your multiplexer going, and thanks for the chip tips, I'll take a look.
Alas, I didn't get away with my trip, a real setback.
PS- no 300mil versions of the multiplexer that I can find from my suppliers. I just bent the first 12 legs out straight and soldered it in as a sip with a 12 wire lean-to.
Fugly!
Or 2x IC Holders, 1x300 & 1x600 on top of each other ???
Bruce, re. the mains monitor I'm busy with: (AS WELL!)
You recommended to use a small PCB isolating transformer with higher voltage out, would 15V be high enough to make the diode drop not to much of a problem or did you mean much higher like 24or48V?
Thanks,
dubbleUJay
48 sounds better. You can skip the transformer if you bond the genset neutral to the mains neutral.
Folks,
A very interesting project you're building here !
I've been looking at instrumentation for my 6/1 listeroid CHP that I'm in the process of building/designing.
At first though your system seemed too complicated for my needs, but on second thought perhaps not.
You know how it is, you start out with a few inputs and then think, "well, you know, this would be nice too...", etc..
For my two cent's worth, I haven't seen any mention of a deadman timer.
My nightmare scenario is having my listeroid start leaking crankcase oil into the upper rings and having the engine overspeed until the flywheels burst.
(It's happened)
The first thing I need is a failsafe engine kill system !
I'm considering a spring loaded decompresser lever that's held in place by an energized solenoid hooked to an overspeed sensor circuit that has a deadman timer in it.
I need to check and see if the Arduino has that capability, and if not design something that can do the trick.
I'll come up with a list of inputs and outputs and see how it compares with your list.
Thanks for all the work on this, I think we'll all benefit by this work !
Daryl
Hi Daryl, yes, this would be a great thing to have if it all works and we keep it as simple as possible. The biggest thing to accomplish seems to be all the various interfacing probes for the inputs. Temperatures up to 125C were no problem, but reading the volts, amps, high temp(exhaust 350C+) and fuel flow is another story, but we'll get there!
I tell myself that if I had to buy a commercial controller/data recorder, I would still have to buy the probes anyway and for that matter if someone wants to buy commercial sensors, they should be able to use them with this project as long as they have/supply an analog output scale of 0-5Vdc to the inputs!
The nice thing about the Arduino is that your "well, you know, this would be nice too..." statement would be easy to incorporate if we have the program/code, so we can do as we like with it. Your "overspeed sensor circuit" would be the Arduino and a lot more! ;)
About the Deadman Switch/Timer, as mentioned elsewhere in this thread, we would have some emergency shutdown outputs from the Arduino.
We could tell it to monitor high temps, AC frequency, Engine rpm, exhaust temperature exec. and if the go out of predefined levels, it would give a shutdown output.
What one then does with this output is up to each guy I suppose. I'll be closing my rack with the existing SOM solenoid as it also opens the exhaust valve as well, but will probably incorporate a secondary fail-safe of some sort as well in the future.
I also thing a software/hardware Watchdog should be in the code to shutdown should the electronics fail, but one should then be able to bypass it for manual operation.
This thread is getting a bit long and the info/ideas is all over the place, once I know myself what's potting, I'll probably write a small preliminary spec of some sort for us to agree/disagree upon ???
Please Daryl, do give me feedback on you list of I/O's, that's what this thing is all about, covering most/all aspects we can think about.
I might have some knowledge of electronics, programming, mechanics exec., but I'm limited on all, so I'm going to need a lot of help with this thing still!
I'm sure it will be worth the effort though.
I think that commercial units are not obtainable by most people due to cost.
Wilhelm
I've found the Pic (Pixaxe) microcontrollers to be incredibly reliable and robust. I one that's been running continuously as a remote PV/battery powered cell phone controller for a few years.
After that pleasant experience, for my Picaxe Listeroid controller project, I decided that one layer of protection was good enough for me. And in fact I think I'm still the only Lister/Listeroid owner with full auto capability with real time monitoring and auto shut down.
The processor monitors oil (high or low), cylinder head temp, rpm, and vibration (Murphy unit I got on ebay). It monitors air pressure so that the engine can be shut down before the 500 gallon(!) tank gets too low. It shuts down if there's a problem via the same air cylinder actuators used for remote auto start and stop. Full manual operation is still supported, with processor off, and I can also start manually, then turn it on. I've run it for a couple years now, zero processor glitches.
I would expect the same reliability from the AVR chips. Where a watchdog timer (processor must reset the timer as proof of life else engine full stop) might come into play would be with an electronic (full control) governor; a failure or glitch could result in overspeed failure of deadly proportions.
Quote from: BruceM on November 26, 2009, 09:38:35 PM
..............And in fact I think I'm still the only Lister/Listeroid owner with full auto capability with real time monitoring and auto shut down................
HOPEFULLY not for to long Bruce! ;)
I've chosen the Arduino AVR for its popularity and all the available info/code/hardware for it on the net.
There's Eagle CAD cct/pcb available for a single-sided PCB, bare-bone PCB so one can build it yourself if push comes to shove! Cellular & wireless Xbee has been done exec.
I just hope/believe I made the right choice so that the project can be easily reproduced!
Bruce, such a lot of thing/ideas has changed since the start of this thread, do you think its a good idea to write a short "abbreviation" and post it here so that we might see where we at and if we agree on things?
I'll wait and see 1st what Daryl suggests on his I/O's though, or do you think its a bit to soon ???
I'd love to get more guys involved/expertize, specially in electronics and programming, not that there's anything wrong with yours, I just know that you're very busy at the moment and I'm going to need some advice/help with coding the Arduino soon! (it's using Processing language, mainly derived from Java from what I gather)
I think its a bit of a pain to go through the whole thread and try and see what its all about, like Daryl pointed out indirectly. ;)
Wilhelm
PS- Bruce, thanks for explaining what a WD was all about, I just presumed everyone knows, what was I thinking! :-[ I would think an external hardware version monitoring a pulsed Output pin to keep it separate from the main board, but that's just because I've done something similar before, as for a software solution, I wouldn't no at this stage ???
Everyone has probably already looked but.... I just tried searching Arduino on ebay....
There are many items! even a "getting started" book!
anyway... just thought it might be of interest for someone.
Rob
I ran into something that might be useful for your project, WJ: It's a chip that does precision RMS calculation. It's the AD737. About $6 US at Digikey.com.
I think the AVR chips and Arduino are good choices, just more challenging for the novice than the Picaxe. I'm not going to be able to help with your code except in generalities- I haven't used either.
Another thought for your project as I was looking for low quiescent current 7805 substitutes for my battery bank charge controller (BBCC):
If you use a PWM regulator from your 24VDC down to 5.5V, then clean off the ripple with a LF50AB or MIC5237, or best, Microchip's MCP1825 regulator. They are all low dropout regulators, with low quiescent current.
My BBCC is designed for extremely low power, so the 5-7 ma quiescent current (constant ground pin loss) of a standard 7805 is greater than the projected nightime power used!
You can reorganize your material anytime you want, just let me know if you need me to help with the cleanup.
Thanks Bruce, I'll definitely look at the power supply/regulator parts and also the rms chip.
I found this site 2day which have a huge selection of ready made sensors and stuff for the Arduino, one can probably buy most of the kit there and the prices seems good.
Particularly of interest to me was this CT power meter probe or you can just get the CT by itself. They have a 30&100Amp version.
http://www.seeedstudio.com/depot/electronic-brick-electricity-meteranalog-p-471.html
Have a look at their "Electronic Brick Kits" & also "Sensors" to the left of the page.
For someone who wants this logger/controller and not make the sensors (or most of them anyway) this could be a supply.
They develop extension boards for Arduino, all one can want by the looks of it and they are busy with a data-logger as well, which might be a bit pricey and not available yet. It has a GPS module on board, but it seems they will take that off to bring the cost down.
http://www.seeedstudio.com/blog/?p=687
I'm going to sh!t myself though if I'm busy re-inventing the wheel and this thing of them are dirt cheap!
Mind you, the nice thing about the Arduino is that most of my code should run on it regardless. :)
It just blows me away what one can do with these things!
About the coding Bruce, I'm battling to read the correct channels from the 4067 as I'm reading 2 values at the same time with just 1 sensor connected to 1 input???
I've asked on the Arduino forum and got some joy, but I'm still having problems. I've been through it a couple of times and will have to go over everything again. :'(
Its a stupid mistake somewhere and I'm going to kick myself when I find it!
Post or email me the code and I'll take a quick look.
Sometimes units always report battery voltage even with no inputs connected, at least that's how the board I'm using works.
I just hooked up mine today but I think I need a different potentiometer, the one I had laying around is a 1K ohm I think and it's really hot. I clamped a pipe wrench on it as a heat sink :-D
I'm using a pot since the board needs analog input to be under 20V and I have a 48V battery bank.
I put a 500A shunt on one of the positive inputs to inverter then to the pot, then to the board.
I fiddled with the pot until 50V reads as 11V or so.
I hooked the board to a serial to ethernet device and plugged that into an old wireless router so I can read the values up at the house.
From there I run my data service ( windows .net c#) that interprets the data from the board and saves it into a SQL server, then I have a website where I can graph the data, interrogate the board, and once I get some relays hooked up I should be able to trigger the generator based on time of day, battery charge and other inputs like ( in the future ) how much water is in my 2600g storage tank so it could turn on the generator and fill it up if it got too low.
I know I'm cheating by not making the board myself but it's from my job :-)
WJ, Nice price on the current transformer, but that's all it is, no conversion to analog 5V scale.
Glad to hear you're making good progress on your data acquisition setup, Jedon!
Got your code and found a bug in setting the multiplexer address.
This brings up an important point- for a novice coder, the Picaxe basic is the easiest to learn and understand. C is not as clear, by a long shot.
AAARRRGGGG!!!!!
Bruce, I can pull my hair out! It's working now, but this is what happened:
1) I originally (before I understood any of the code) copied code from a 4x 16ch 4067 project and it didn't count correctly.
2) Obviously that portion of the program was incorrect so I changed it, but still it didn't work!
3) I made the changes you suggested, but still no go!
4) Then I saw it was only the 3rd bit that didn't change, found a soldering problem pulling that output to ground, problem SOLVED!!!
I had the correct code all along, but just presumed it was the same fault, incidentally yours work and 2 other "ways" I was using also works.
So I was going in circles all the time!
I must say that I only understood the way it was done once I looked at your code from the 2nd email, thank you very much. :)
I'm going to be so forward as to email you a short Arduino Programming Handbook if you don't mind,
if you do, I'm sorry, its already on its way! ::) ;D
It sounds like there's a better way of addressing the outputs, but I cant find any reference on the net as how to do it, maybe you can point me as it does have a BYTE "command" that you asked me about elsewhere?
I can now take all the extra code out that I used for testing it and make it as small as possible, just one question, would one save the values read by this routine into an ARRAY to be accessed by the rest of the program or is there a better way to store them?
Thanks again, I feel much better now on this Sunday afternoon, I thought I'm going to start my Monday with a blueish color ;)
Wilhelm
I looked at the manual; the Arduino language does not have a byte output!!! Perhaps you can find the code in in someone's library. You can code around the problem, but good grief, what an oversight. You could always just use the AVR C compiler, which is reportedly very good. Perhaps Arduino allows calls to AVR C routines- but I don't know.
Since you couldn't just count and output the mux address as an upper bits masked byte, it made the code a lot more involved and confusing, having shuffle bits for write to pin commands.
Yes, I'd store the values in an array for easy access.
The two problems at once situation is always a hair puller and time eater, glad you got it sorted.
Thanks again Bruce!
There must be a good reason for not having a byte output or its not mentioned in the "3rd party" manual.
I presume with the enormous following of the Arduino, someone would've complained in the beginning about it.
I'll see if I can find reference to it somewhere. When I asked about the 4067 problem on the Arduino forum, the one guy also mentioned that it was a crappy way of addressing the multiplexer, but when I asked him how he would do it then, he never came back to me! ::)
3x projects I looked at using multiplexers on the Arduino used this way to do it.
OK, now I have a micro with the following I/O still free or to use:
10x Digital I/O pins (4x PWM capable)
5x Analog I/O pins (Original)
16x Analog I/O pins (Extended)
1x Voltage reference pin for Analog inputs (AREF)
and I still have access to I2C bus if I need it in the future.
Once I've cleaned up the code for the multiplexer, I can continue with the important stuff like the various probes! ;)
I did a little looking for you, WJ. Arduino "language" (bastardized AVR C) does support AVR C routine calls, since the Arduino language is so limited.
Here's a link to the info you need to do byte outputs to the AVR chip ports:
http://arduino.cc/en/Reference/PortManipulation.
Quote from: BruceM on November 30, 2009, 04:18:25 AM
I did a little looking for you, WJ. Arduino "language" (bastardized AVR C) does support AVR C routine calls, since the Arduino language is so limited.
Here's a link to the info you need to do byte outputs to the AVR chip ports:
http://arduino.cc/en/Reference/PortManipulation.
Thank again Bruce, sometimes I don't know "for what or how to" search for the info that I need.
By that I mean, I know what I want to do, but with English, acronyms and being a novice at code, I think you can imagine how I feel! :'(
I'll see if I can use the info on that page after I've read it a couple of times.
Ultimately I want the code that reads the 4067 inputs as short as possible because it should run fast and continuously all the time.
You don't need to worry about speed, the code is compiled and is plenty fast enough, just primitive. You can use your bit version that works without concern.
If you want to learn the write a byte to a port code later, I'll help.
Folks,
I started making up a list of useful I/O signals that we could use for DA/Control.
I've come to the conclusion that we should make the I/O as general as possible.
Since each user will have different needs and wants, I think both the hardware and software will need to be modular so each application can pick and choose what's applicable to their situation.
I'm likely telling you what you already know, but I always find that a project goes together better when the framework gets nailed down first.
I think we can separate the code into two sections, the first for control and the second for acquisition.
The controller code can be in two sections, engine control and auxiliary control.
The engine control code can be split into three sections, startup, emergency shutdown and controlled shutdown.
The auxiliary part can cover fuel, temperature, pumps, charging, etc.
There is less chance of code failure if you keep each section simple and easy to understand and analyze.
The acquisition part is quite a bit simpler in complexity, but a lot worse in how to handle the I/O and what to do with it.
Are we going to use a PC to store the data, or some memory device or both.
There is some advantage to storing some of the data at the microprocessor level, such as memorizing the "states" of some of the variables,
For example: is the engine running right now or not (say after a power glitch - don't want to try to start a running engine, or which pumps were running when the glitch happened, etc.)
And what do we use to move the data ? Ethernet, RS232, Wireless, etc...
Which of course implies some sort of PC front end (HMI, Human Machine Interface)...
Can be as simple as a display of current values to a full-blown "click here to to turn on the main circulation pump" or "click here to automatically start the correct pumps and valves to heat the house to 72 Deg. F."
After all that, here's a list of potential I/O for the system, not sorted by digital or analog input or output:
Inputs:
RPM, Oil Lvl, Oil PSI, Coolent Temp's, Exhaust Temp's, Vibration sensor, AC voltage X 2, AC current X 2, DC current, DC volts, Frequency of AC power (HZ), Fuel flow, Fuel lvl, Shutdown switch, Crash Shutdown switch (emergency stop), Generator Temp, Start lockout, Fuel flow in/out, low fuel switch, Fuel temp, Engine temp.
Outputs:
Shutdown, Starter, All OK, Fuel changeover valve, glowplug, generator overload, Alarm condition, Horn, Alternator field on/off, fuel cutoff, throttle, Alternator to main power contactor
Idiot lights:
Oil lvl/pressure, temps OK
Things that it might be good to store in micro:
Hours runtime, watthours total, fuel valve changover state
More can be/should be/might be added to the list.
I used to do this for a living, so you can see I've got a certain "approach" to the system that's industrial in nature, and likely way, way overboard for what we want.
I hope this adds a little to the discussion, I'm not really sure where you all are on the design of this thing.
It might be a good idea to list what hardware is going to be used, and a list of what is available in the form of digital and analog inputs, as well as what exact type of microcomputer is being used.
I've got a nice relay rack that's looking for a new purpose in life. :)
Daryl
Good to have your contributions, Daryl. WJ hasn't started on engine control, his priority was data collection. His ass is covered, hardware wise, as he has I2C expansion available which can add any DI/DOs and analog he might need.
I can provide my Picaxe Basic source code for the operational code base. It's been in service for a couple years. It's fairly decent and documented, bug free. It has no data logging, except status logging via a serial opto-isolated current loop (cat5 cable) to the remote control panel.
I'm inherently skeptical about software and controller hardware when words like "group", "we", "open", "universal", an "generic" are used. Watched Motorola blow over 5 million on such software fantasies, 3 years later a total loss.
For an engine controller, no one's suite of sensors, actuators is going to be the same, but obviously there can be some sharing of hardware and software.
BruceM,
I've looked pretty closely at your design, and I like it.
Myself, I'm like you, KISS principle first, get it working, then add on the fancy stuff.
Pic's are rugged as anything and I do love the Picaxe chips - I've got several on my workbench right now that I've been working with.
My only complaint is the language limitations, but at least I don't have to learn *another* proprietary language to get the job done... :)
I really like the idea of a Picaxe to do the control, and something else to do the DAQ part of the system.
Pic's are so tough, hardware wise, and the language is so simple that I think it lends itself well to a critical system like engine control.
The last few jobs I worked on used a distributed control system, and I fell in love with the ruggedness of the systems.
Any failure isolated itself to that particular subsystem, so that the rest of the system kept running.
Since I'm the guy who'll have to do all of the repairs, I want everything as simple as possible.
I'm thinking about a Picaxe/Adrundo communications link.
You mentioned opto-isolated links for communications, what exactly did you do ?
I'm a bit shy of Ethernet due to voltage drops/potentials across the lines.
Yah, Open Source... More of a CYA for code reuse so far as I'm concerned.
Still there is a lot of good software coming out of open source development, I'm just uncertain how well it will work on the hardware side... ::)
It's still an experiment, IMHO...
Daryl
dubbleUJay,
What parts are you currently using or planning on using ?
I'm trying to get an idea of how many digital and analog I/O's will be available.
Thanks,
Daryl
I agree, Daryl, divide and conquer (mulitprocessor) can sometimes speed things along greatly. It might apply to WJ's situation, depends on his operations vs data recording needs.
I'm not pushing the Picaxe on anyone, I'm glad to try and help out with whatever toys the boys like. :)
I agree the Picaxe Basic is very basic (though better than Parallax Stamp), but again, it's just an pokey engine controller where the lack of arrays and floating point math are not traumatizing. It just forces you to keep things simple, which isn't a bad thing for a simple controller. The same code could be rewritten in Arduino or AVR C. I think AVR C makes more sense if one was bothering with a rewrite; Arduino is too rudimentary and Arduino mixed with C seems a bit of a frig.) Another option would be to use the 40X2 Picaxe as a I2C slave (or master) along with the Arduino. You get a boat load of I/O on the 40X2 chip, almost all reconfigurable as in, out and analog, and you can always upgrade to a Compiler (almost any language) later if you decide to get fancy.
Regarding my communications link- it's a matched impedance, opto-isolated current loop. (Dirt simple and cheap.) It runs at only 600 baud, though it will certainly go 2400 baud or better. (It is limited by the filtering of my processor board in my setup.)
I went the opto-isolated current loop route as the Cat5 cable is very long (560 feet), and run in the same steel conduit with my AC power. (A no-no, but I didn't want to do another 560 foot of conduit run.) I wrote some serial loopback test software and then fired up the big shop central vac (brushed motor makes mega EMI.) Zero data errors.
I'll find the schematic for it and post it. Glad to help modify it for your needs.
Another rock solid serial link is using plastic fiber optics; you'll never have EMI or lightning issues with fiber. Industrial fiber optics makes cheap plastic LED/photodetector emitter/receivers ($3-4 each), and you just cut the fiber with a razor blade, then shave it smooth. It's great stuff. I couldn't use it on my Lister project as about 400 feet is the distance limit for plastic fiber. I like and use multimode glass fibers a lot, but the transmitters and receivers are spendy and take too much power for my Lister application.
PS- Regarding the schematic- sorry it's hand drawn but I was having vision troubles at the time and computer use was a bitch. My processor is in shielded enclosure with 10K ohm impedance, LC filtered connectors for the data lines. I do this because my brain is fried from MS and epilepsy and I can't do the debug work near a running processor otherwise. If you get rid of that, you don't need the buffer to drive the signal, and it just becomes two 200 ohm resistors on the driven end. You get better noise immunity with matching the impedance on the pair, though it isn't absolutely necessary. The PC123 optoisolator is cheap, fairly fast and only takes a couple ma to light up, the resistor across it's inputs increases the current requirement a bit to improve noise immunity, also. Obviously, the other end, my remote display of LEDs and switches is exactly the same circuit for TX and RX, and is in fact another 40X1 (the X2 wasn't out yet).
Daryl, I just got this and have to read your post thoroughly, I just have to go to town 2day and I'll post a bit later this afternoon.
i too have been following this thread with some interest, i am always amazed at what folks do with controllers
and the numbers of such to work with, compounded by the different programming languages and then the
millions of ways of using all this to approach a problem.
the more i look at what is being presented the more i think i am staying in the multiprocessor (master/slave)
camp, not because i see anything wrong with what you guys are doing, but rather because of my shortcoming
in ability to program to that level of complexity.
even the various serial communication protocols seem to be of questionable use to me, one you start onto the path
of the master/slave architecture it just seems easier to me to just use simple "hi/lo" on a wide buss.
for instance you have a master, it only job is to scan and make decisions, and once a decision is made
it sets a line on the buss to "high" and the slave attached to that buss line which has been in a short loop
breaks out and starts to do its specialized operation.. this leaves the master to carry on scanning all manner
of stuff, making decisions and sorting out requests to start and issueing permissions to start.
it seems to me that the master can then have such a simple program loop that doesn't require a bunch of math
computations, or conversions, lookup tables, etc. so that the likelihood of a lockup would be greatly deminished?
so the master just keeps on trucking, doing its thing and the slaves can do the intricate detailed work to handle
very specialized operations, such as engine autostart, warm up, glowplugs, fuel solenoids etc etc. and while doing
so have a line of code that has to be bumped every so often so that the master knows the slave is not locked
and continuing to do its thing, if the expected high is not on the buss line when the master rechecks, then it can
intiate a shutdown. that sort of thing.
it just seems so easy to break the work load up among several processors and program them to react to commands
and report back periodically so that the master can maintain control, and also setup a failsafe so in the event the master
should fail the slaves can take over and effect a shutdown.
i am sure you smart fellars can do this all on one microcontroller, but it is so far beyond my capabilities and my interest
to learn at this point in my life that it isn't even funny.
now having said all that, what i think would be very cool would be to at least agree to a buss architecture that would be
very simple as described, that way everyone that decides to build whatever processor controlled project could take it
and plug it into the buss and get it to play well with others built by other folks using different microprocessors and different
programming languages.
last count i have my system laid out to have one master and up to 7 slaves to manage a complete system from loads
to power sources.
looks like i might have a bunch of free time on my hands in the near future while healing up from surgery, so i guess i will have
time to further develop my simplistic view of what an automated world should look like.
:)
bob g
Bob, Nothing wrong at all with your strategy, and that's just how I designed the first multi-microprocessor flight simulator (a technology demo for the U2/TR1) back around 1980. It had 8 microprocessors with hardware floating point coprocessors. Every processor had it's own private hardware bus for all of it's cockpit hardware interfaces, plus a fast 8 bit wide block transfer capability to the master. It ran at a 15Hz frame rate, with the flight model split in two processors. A single PC would run circles around it now, of course.
Regarding: "master/slave architecture it just seems easier to me to just use simple "hi/lo" on a wide buss.". Sure, if a slave function is as simple as do it or don't. But most of the time at least status information and often some data is needed back by the master. A common serial (or byte wide parallel) communication bus solves both problems.
The PICaxe 40X2 parts (or AVR or PIC with compiler) would make a widely distributed architecture fairly easy by supporting I2C buss between processors. That gets you 400KHz serial via the chips hardware, so less impact on processor time. SPI bus is even faster, and might be used the same way. The routines for the PIC chip's hardware I2C are direct in the basic language of the 28X2 and 40X2 Picaxe chips, I've used it, it works fine. The only fly in the ointment is that with only one I2C bus in hardware per chip, you'd have to avoid I2C expansion chips on the slaves. Or add some hardware to do it, such as gate the I2C pins to a secondary bus and then switch to master mode. If using chips like the 40X2, it seems unlikely a slave would need I2C expansion anyway.
But for an engine controller, it's hard to imagine the need; a single processor or can do the job without a fuss, or any backflips. My Lister controller doesn't use a single interupt, even. Just write the code for each of your little tasks, as if you had a processor for each and then I'll give you a hand in combining them. It's only daunting the first time. :) If you're dong battery and power management, too, then I can see dividing things up more. Dedicated serial data links (like my simple opto isolated current loop) can be used for that sort of division, as there isn't much data involved, and it isn't very time critical.
The reliability and durability of the PIC processors is legendary, and I think most of the others are damned good too. My fiber optic link, Picaxe 18X cell phone controller is out running continuously in a somewhat insulated doghouse off it's battery and little PV panel, glitch free for two years and counting. You don't need to worry about redundancy or anything else. If you program it simply and well, and your hardware put together decently, it will run and run and run without a hitch. Micros only seem unreliable to you because you're a hands on guy and you need more hands on micros time. :)
Quote from: Crumpite on November 30, 2009, 06:40:21 PM
dubbleUJay,
What parts are you currently using or planning on using ?
I'm trying to get an idea of how many digital and analog I/O's will be available.
OK Daryl, this is what I have at the moment: (As I mentioned before, my intentions is to keep the non-electronic guys in mind, that's why I chose the Arduino as a base system board, popularity and info available for the novice is plentiful IMHO)
There's more info than you asked for, but I'll have to post it all together some time anyway. ;)
Hardware: 1x Arduino Duemilanove (ATmega368)
1x Extended Analog Input board (16ch HEF4067BP Multiplexer)
If one don't need to many sensors, you don't need this extension board!
OK, now I have a micro with the following I/O still free or to use:10x Digital I/O pins (4x PWM capable)
5x Analog I/O pins (Original)
16x Analog I/O pins (Extended)
1x Voltage reference pin for Analog inputs (AREF)
and I still have access to I2C bus and a few other goodies if I need it in the future.
Probes I have in mind with these inputs: 1x AC Volts/Amps/Power (extApin0&1) (Alpha)
1x Thermocouple for Exhaust (extApin8) (Alpha)
7x TempSensor(LM35or36) (extApin9-15) (Beta)
1x Engine RPM Sensor (Opto-???) (extApin7) (Not Started)
1x DC Volts/Amps/Power (extApin2&3) (Not Started)
2x Digital Inputs Fuel-/H²O Level (Not Started)
1x Oil Pressure Sensor (Maybe) (extApin6) (Not Started)
Controller: (I'll get to this later and might use a dedicated micro for it.)
1x Digital Output Emergency Shutdown (Not Started)
I've got the Arduino and multiplexer setup and some code for it to read the extended values:
// START of: 16 Channel Analog Input Extender
// Extended Analog Input pins 0to15 = ExtAin[0] to ExtAin[15]
// Some TEMPORARY CODE for testing to serial port, to be deleted later.
byte chActive= 16; // The number of channels active.
byte chNumber= 0; // Keep count of the channel number to read.
int currentVal= 0; // Current Value of channel
int ExtAin[15]; // Store 16x Extended Analog Input values in Array here
byte binA0 = 0; // Set initial Address Input values for 1st bit A0
byte binA1 = 0; // Set initial Address Input values for 2nd bit A1
byte binA2 = 0; // Set initial Address Input values for 3rd bit A2
byte binA3 = 0; // Set initial Address Input values for 4th bit A3
void setup() { // Setup Digital Pins & Serial COMM's
pinMode(10, OUTPUT); // Set Dpin to Output (A0 <-> pin10)
pinMode(11, OUTPUT); // Set Dpin to Output (A1 <-> pin11)
pinMode(12, OUTPUT); // Set Dpin to Output (A2 <-> pin12)
pinMode(13, OUTPUT); // Set Dpin to Output (A3 <-> pin13)
Serial.begin(115200); // Set Serial COMM's to PC
}
void loop() { // Get 16x channel Values
// Loop through the 16 channels and read each one.
for (chNumber = 0; chNumber < 16; chNumber++) { // Address ch's & read values
// Generate Address Inputs for HEF4067BP A0 to A3 (pin 10 to 13)
binA0 = (chNumber & 1); // Create 1st bit for Address A0
binA1 = (chNumber & 2)>>1; // Create 2nd bit for Address A1
binA2 = (chNumber & 4)>>2; // Create 3rd bit for Address A2
binA3 = (chNumber & 8)>>3; // Create 4th bit for Address A3
// Send current Address Inputs to Multiplexer
digitalWrite(10, binA0); // Set bitA0 on pin10
digitalWrite(11, binA1); // Set bitA1 on pin11
digitalWrite(12, binA2); // Set bitA2 on pin12
digitalWrite(13, binA3); // Set bitA3 on pin13
// Read the common I/O pin0 value for current channel
currentVal = analogRead(0);
// Write Current Value to Array index position
ExtAin[chNumber] = currentVal;
if(chNumber < (16-1)) { // Step through all 16 channels until end
//Serial.println(""); // TEMPORARY CODE: Continue next Print from next line.
}
else { // Start over
// TEMPORARY CODE:Serial Print Channel Values stored in array
for(int indexStep=0; indexStep<16; indexStep++) // TEMPORARY CODE: Index step for array values
{
Serial.print(" ;"); // TEMPORARY CODE
Serial.print(indexStep); // TEMPORARY CODE: Print Channel Number dirived from current Index Step
Serial.print("-"); // TEMPORARY CODE
Serial.print(ExtAin[indexStep]); // TEMPORARY CODE: Print Value for current Channel
}
}
}
// TEMPORARY CODE: Take a break (1000 = 1sec)
Serial.println(""); //TEMPORARY CODE
delay(2000); // TEMPORARY CODE: Wait a while before starting over
}
// END of: 16 Channel Analog Input Extender
For some reason I cannot may the display of the code bigger, sorry! :-[
I've got the code for Temperature, also Vac, Aac & Power and most of the other probes, its now a matter of incorporating it into the code above. (Once I've got all the sensor hardware sorted)
The 16ch Multiplexer board is straight forward & you can probably buy one similar somewhere ready made, cct & board at the bottom of this post. Its not final & I've got it built on a Vero-board at the moment and I will most probably add more things to it, for starters a 5V PSU as to keep the supply voltage away from the PC USB port.
For now the various values are printed to the serial port and written to a file with a program called "gobetwino".
From there I use a real-time graphing program (Kst) to extract the data and display it or I've used MS Excel to do the same thing. (OpenOffice would probably do it as well, just haven't tried it yet)
Hope this answers your question Daryl ;)
Wilhelm
Nice work, WJ.
Thanks Bruce, I must say that without your help I would've never gotten this far with the project!
I saw that question about the 10k's seconds before you took it off ;)
I'll leave them in for now until I'm sure which inputs I'm going to use. Maybe suggest a switch array in the final version like you said.
It's just easier switching an input "off" or to "0" than changing the program to not read it every time.
That's why I was pushing it with a 100k so that I might leave them in if they didn't influence the signal significantly, but like you said, it will. :'(
I'll firstly incorporate the code for the temp sensors as I have that all working.
Then I can carry on with the cct for the AC Volt-Amp probe, I'll have to read through our conversations again about it and come up with a solution. There is just so many ways to do it and I'm not sure which one to chose ???
Bruce:
that was precisely what i had in mind, that being the use of a slave dedicated to each of numerous subsections of the system
such as
the master to scan loads and determine the best power supply for that load or combination of loads
a slave to do the engine management
another slave to manage battery and inverter issues
other slaves for control of other power sources such as wind or solar, alternator control, etc.
another slave to manage hvac loads,
other slaves for refrigeration loads, water management (well pump or containment supply)
other slaves for thermal storage etc.
and the list could go on depending on size and complexity of a system.
basically a master could be programmed to scan loads and determine for instance that the refrigerator needs
serviced (power provided), the well pump needs to start, and someone happens to have just started the washing machine
under this set of demands it is likely that providing the power would be most effective "if" power from the wind is low, it is cloudy, or
there is also need to do some battery charging, and there is a use for the excess heat recovered from the exhaust, then go ahead
and issue a command to start for the genset,
if on the other hand the loads are determined to be such that the duration is short, and within the capability of either the batteries and inverter, or windpower at the time, or solar at the time, then issue a command to connect the appropriate power sources to the load
and not start the genset.
i can envision many different combinations of loads and power sources being able to be sorted and a determination of the best match
being determined by the master in a relative short amount of time, and control could have taken place quicker than i could use a pencil
and paper or check a chart and connect things myself. and at least things would follow a standard flowchart and be done the same way
each time, leaving out the human factor of not only myself but the wife or others.
also it is fair to note, that rather than reinvent the wheel i am of the "group" that subscribes to integration of existing and appropriate technologies where i can into the system, items such as a balmar controller is much easier for me to deploy than building my own controller and working out its kinks, at least in the beginning stages. at some point down the road however i might well find that a more
specific design that fits my need would serve the purpose better and then i could set out to design and build such a controller, safe in
knowing that i have a balmar controller that just works i can fall back on.
as for I2C protocol, i suppose it would be prudent not to paint its use out of the corner but leave it as a possibility should
i find it useful down the road?
as for your early experience with flight simulators and multiprocessors, i did some reading in the use of such back in the day to
do all sorts of stuff, looks to me that if it was good enough back in the day to get things done for a flight simulator or put man
on the moon it surely ought to more than adequately provide all my control needs today?
before i started in with the BS2 stamp i had to work with basic relay logic, and either electrical or mechanical timers and the like
so making the move to the stamp and its pbasic was very much like making a quantum leap for me. i just figure that if i could do
it with basic relay logic and electromechanical means then i need to fully exploit the very basic means of control (relatively speaking)afforded by the stamp before i worry about trying to get it all done on some incredibly fast processor using many pages of very
complicated codeing (again relatively speaking)
i am thinking it is unlikely that i will outgrow the capabilities of the BS2 stamp anytime soon, most especially in a master/slave system
where the number of I/O would be quite staggering compared to the actual needs of even a fairly complex system. (again relatively speaking, 7 slaves x 16 I/O = a bunch)
this also leaves me the possibility in the future to adopt something like a pic controller should the need arrive to do a specific slave
where the pic would do a much better job and have that slave integrate into the system as a whole, and still have the fall back position
of a known working slave based on the bs2?
a lot for me to think about and consider, i am already 30 plus years behind the curve, and the curve it moving away from me
at a very fast clip!
:)
bob g
Bob, I see that one can get a Arduino like node called JeeNode which has a few I/O's and its wireless. Can be programmed with the Arduino code.
It was specifically made for Node applications for users that just have a few I/O's at certain places where Xbee would be overkill and expensive.
http://news.jeelabs.org/projects/
One can build a barebone Arduino and put whatever comms you want to use onto it as well.
The thing is with all these multi micro systems is that you get to a stage where you need a killer application to run it all because it gets so big.
I've seen this in Home Automation packages for free and commercial, IMHO anyway. I still have to get a UI for this project of mine in the end when all the hardware is working.
I'd avoid wireless except were no other viable alternative exists.
Bob, I'd love to wean you off the Basic Stamp, it's real time capabilities aren't nearly as good as the Picaxe's, and it costs 4x as much. The 40X2 is $10, and has 32 I/O, and can handle serial data with timeouts via hardware (doesn't tie up or hang the processor), and has other real time support that is better, including servo control done via timer hardware that doesn't tie up the processor. I draw the line in functionality at having a timeout for serial input; no hava, (ala Basic Stamp) no use to me, and I'm not frigging with an external interrupt or timer to work around it. If a vendor is too stupid to realize the need for timeout on serial input command, they just shouldn't get your business. The basic language is almost the same for Stamp or Picaxe, in fact their program editor has a Basic Stamp code mode, and you'll find first class help on their forum. I never had a question that wasn't well answered the same day, they have tech support staff that are on the ball. I'm just thinking about how to make your job easier for you. The Stamp is a handicap you don't need. Now I should shut up about it! ::)
Your plans are reasonable, certainly it should be distributed to a few different processors, just to make it easier to tackle. How far apart physically are the processors? Distance is an important factor in deciding how to communicate, as well as speed requirements. A simple asynchronous serial bus (9600 baud or less), 2 pair and two signals on Cat 5 might be all you need. Or even less if the distance is short.
I must say this thread has grown as much as your project. Nice Work!
A lesson I learned was not providing failure mode status. The system could shut down from any of six different failure modes and I didn't have any indication of what shut it down. It wasn't as apparent after failure as I thought it would be. After chasing my tail and scratching everything I had to scratch I created an 8 bit status register on the flash RAM, assigned each bit a failure mode, created an interrupt to bit-wise OR the register once a failure was detected and display the word. Only then did I discover an intermittent drop in a dirty flow sensor signal. Of course, this can be done with extra d i/o's as well.
Post failure diagnostics is on the top of my list forever more :)
By the way, I'm a PIC guy. I run my world with a 16F877A
Dave
Dave,
Thats same PIC chip is the 40X1 picaxe as I recall. (My memory is VERY leaky.)
What's your favorite compiler(s)? Your review would be appreciated. I have some upcoming projects (a hybrid ultra low EMI resonant inverter design) were I need a compiler. Boost C is cheap and seems adequate, but I was disappointed that floating point (not needed for the inverter) was only by library call, and the documentation was only so-so.
WJ's been a boon for the forum, and I really value his contributions. He's picked some good gear, and is making good progress, which is fun for us all. There's nothing like an ongoing forum project to keep all of our braincells stimulated. His project is much more mainstream than what I'm working on right now. When he's done, I'll help clean up and make a special project thread so all our ramblings don't distract. So you don't need to thank me, WJ, it's the other way around! Thanks!
Bruce:
the distances are very very short
actually i am planning on using a rack mount drive case, that has 8 bays
into which i am using ide drive caddy's that are removable
the ide cable that attachs to all 8 drives will be my buss, and the power supply
has both the needed 5 volt supply and also the 12volt supply needed for my little relay
boards.
the caddy's are just big enough internally to use available relay boards and also a daughterboard
that will socket my BS stamps.
this setup will allow me to withdraw a single processor unit to allow for bench programming, and then
reinsertion, or if need be removal and reassignment by reprogramming for another use should the
need arise.
i am kind of committed to this direction mainly because i have all the hardware bought and ready,
all the relay boards with parts, the daughter boards, the processors, caddy's and bays, along with
a very nice rack mount case to house it all. i also have all the external terminal strips and some nicely
shielded cable that is 24 twisted pairs to interface with the outside world of heavy contactors/relays, solenoids
and all the other stuff to be controlled.
i am not married to the bs2 stamp, just have them already and understand them well enough to get done
what i need for now, however i certainly see the attraction of the pic processors and would like to work with
them in the future perhaps to replace certain elements of the system where they could do a better job.
thanks for your input it is appreciated
bob g
BruceM
I haven't moved on to the picaxe world yet because I use an old MPLab ICD programmer/debugger at home. I'm locked into 16F pics and MPLab ver 6.2, the last version that supported this programmer. I upgraded my monitor to allow the A suffix pics but that's as far as I can go until I spend more $$ and don't see the need. the 16F84 handles the small jobs and the 16F877 can certainly take care of the rest :)
I haven't used Boost C so I can't comment on it. Floating point can be done without the library of course but it takes a few steps to get there.
I mainly use MELabs pic basic pro but also use microchip pic c from time to time, depending on what I want to do. I started with the c but found the basic pro on epay for a song and never looked back. Purist programmers beat on basic but I find it easier to get the job done for the most part. Assembly will make a nice, compact load but takes many steps to get there and is cumbersome to correct errors. I was into the 68HC11 assembly and Z-World dynamic c before I found pic's.
At work I use a borland c++ compiler, LabView and VB.NET
Not to get into that same old pissing contest but the stamp runs half throttle compared to the pic. I have several coworkers that cut their teeth on stamps and they stay with them and that's fine by be. They are set up and rocking so why change. I stay with what I know as well :)
Dave
Bob, your use of IDE cable and hardware is ingenious! A great design, with all that great hardware and connectors for a song. I'd love to see some pictures.
You have mega wires to play with for your "bus", you can do whatever you need, even dedicated interface to any processor. Since the distances are short, you probably could do I2C on two wires of your bus, but as you previously suggested, some dedicated signal lines and maybe a TTL serial line pair or two would suffice. You don't need twisted pair, you're sitting pretty with your IDE "bus".
With that nice mechanical design, no wonder you're ready to add processors!
Bravo, Bob!
Thanks for the report, Dave. I also prefer Basic somewhat over C, myself, because I'm very short term memory impaired now, and can't keep hundreds of lines of code in my head like I once could. It's just a little easier for me to read and keep track of. I can't swing the price of Microchip's MPlab and Basic, but I really like the look of Swordfish Basic for PICs from England. It a nice structured basic, full featured.
I'm with you on "go with what you know", too. Lots of ways to skin the cat, and just getting the job done is the important part.
Thanks for the heads up, Jens. I saw the post and it sure sounds like support is not there anymore. Swordfish now smells dead and 3 days old. There's nothing as frustrating as getting screwed by other peoples software (OPS).
Fortunately there are many options in PIC compilers.
OK guys, I've got the temperature code integrated into the "Main Code" (Multiplexer)
I'm now reading and writing to file, the last 6 channels on the Extension Board with LM35 Temperature Sensors converted to Celsius (0-125degC), but its easy to change to Fahrenheit as you know. I still need a circuit for reading up to about 450C for exhaust temps to finish the temperature side of things which will have 2x inputs allocated for it.
The code probably need some work to make it shorter, but I'll leave that for last.
Here's the current code if anyone is interested and if anyone sees a problem or a better way to code something in it. please let me know, I'm learning from this. ::)
Also let me know if its OK to present the code this way or should I use an attachment ??? I don't wanna "p" anyone off! ;)
/* PC DataLogger(Real-time) & Engine Controller(Stand-alone)
for Micro Co-Generation Systems by dubbleUJay
Forum thread: http://www.microcogen.info/index.php?topic=188.0
Current Status:(v0.23 Alpha)
Hardware:
1x Arduino Duemilanove (ATmega368)
1x Extended Analog Input board (16ch HEF4067BP Multiplexer)
Probes:
6x TempSensor(LM35or36) (extApin10-15) (Beta)
2x K-type Thermocouple (extApin8-9) (Alpha)
1x AC Volts/Amps/Power (extApin0&1) (Alpha)
1x Engine RPM Sensor (Opto-???) (extApin7) (Not Started)
1x DC Volts/Amps/Power (extApin2&3) (Not Started)
2x Digital Inputs Fuel-/H²O Level (Not Started)
1x Oil Pressure Sensor (Maybe) (extApin6) (Not Started)
Engine Controller: (Not Started!!)
1x Throttle Control Governor (Not Started)
1x Digital Output Emergency Shutdown (Not Started)
*/
//------------------------------------------------------------------------------
//----------------START of: 16 Channel Analog Input Extender--------------------
// (Extended Analog Input pins 0to15 = ExtAin[0] to ExtAin[15])
byte chActive=16; // The number of channels active.
byte chNumber=0; // Keep count of the channel number to read.
int currentVal=0; // Current Value of channel
int ExtAin[15]; // Store 16x Extended Analog Input values in Array here
// Set initial Address Input values for A0 to A3 (bits 1to4)
byte binA0=0;
byte binA1=0;
byte binA2=0;
byte binA3=0;
void setup() { // Setup for Multiplexer
// Set Digital pins to Outputs
pinMode(10,OUTPUT); // (A0 <-> pin10)
pinMode(11,OUTPUT); // (A1 <-> pin11)
pinMode(12,OUTPUT); // (A2 <-> pin12)
pinMode(13,OUTPUT); // (A3 <-> pin13)
Serial.begin(115200); // Set Serial COMM's to PC
}
void loop() { // Get the Analog Values from Multiplexer
// Loop through the 16 channels and read each one.
for (chNumber=0;chNumber<16;chNumber++) { // Create Channel Numbers
// Generate Address Inputs for HEF4067BP A0 to A3 (pin 10 to 13)
binA0=(chNumber&1); // Create 1st bit for Address A0
binA1=(chNumber&2)>>1; // Create 2nd bit for Address A1
binA2=(chNumber&4)>>2; // Create 3rd bit for Address A2
binA3=(chNumber&8)>>3; // Create 4th bit for Address A3
// Send current Address Inputs to Multiplexer
digitalWrite(10,binA0); // Set bitA0 on pin10
digitalWrite(11,binA1); // Set bitA1 on pin11
digitalWrite(12,binA2); // Set bitA2 on pin12
digitalWrite(13,binA3); // Set bitA3 on pin13
// Read the common I/O pin0 value for current channel
currentVal=analogRead(0);
// Write Current Value to Array index position
ExtAin[chNumber]=currentVal;
}
if(chNumber<(15)) { // Step through all 16 channels until end
}
else { // Step out of loop to next task
delay(10); // 1000=1sec
}
//--------------END of: 16 Channel Analog Input Extender----------------------
//----------------------------------------------------------------------------
//--------------START of: LM35 Temperature Sensors (°C)-----------------------
// 2x K-type Thermocouple Devices (<400°C) & 6x LM35 TempSensors(<125°C)
// (Extended Analog Input pins 0to9 = ExtAin[8] to ExtAin[9])
// (Extended Analog Input pins 10to15 = ExtAin[10] to ExtAin[15])
// Code for LM35 Temp Sensor connected to ExtAin[10] to ExtAin[15]
int tSenLM35=10; // The Starting LM35 Sensor Number
int tValue=0; // Current Value of Temperature Sensor (Celsius)
int mArrayVal=0; // Stored Multiplexer array Value
int tValArray[6]; // Store calculated Temperature values here (Celsius)
int tV=0; // Integer for Temperature Value selection
// Serial Print START-string for GoBetWino
Serial.print("#S|LM35TEMPS|[");
Serial.print(" ");
// Loop through the LM35's & calc the temp from stored values in Mplex Array
for (tSenLM35=10;tSenLM35<16;tSenLM35++) { // Create LM35 Xpin numbers
// Get selected LM35 Sensor value from Multiplexer Array
mArrayVal=ExtAin[tSenLM35]; // Get stored Multiplexer value
tValue=(5.0*(mArrayVal)*100.0)/1024.0; // Convert to Celcius
tValArray[((tSenLM35)-9)] = tValue; // Write LM35 Value to Temp Array
// Print to serial port
Serial.print(tValue,DEC);
Serial.print("; ");
if(tSenLM35<(15)) { // Step through Ext Analog from Xpin10 until end
// Return Values to zero
tValue=0;
mArrayVal=0;
delay(10); // delay before loop
}
else{ // Serial Print END-string for GoBetWino
Serial.println("]#");
delay(1000); // Delay before starting over
}
} // END of: LM35 Temperature Sensors (°C)
} //------------------------------END of CODE-----------------------------------
Bruce, I need some help with the DC sensing cct please. I've been following the thread by Jedon about scaling from 48-5V and I decided its probably wise to do mine at the same time as its more or less the same thing. (You know, there where I made a few mistakes with my postings! ;) )
I'll carry on with the VAac-, RPM- & 0-450C Temp sensor after this one.
I've taken the ccts you presented there and came up with the following diagram to read 0-30Vdc & 0-30Adc.
Its not at all a working model and I just want to know if I'm on the right track for my application please?
I'm probably going to need some help with the calculations for the resistors as well if you have the time please ??? Cct diagram at the bottom.
Thanks to all who's helping here guys, much appreciated!
Daryl, I haven't forgotten about the things you wrote a few posts ago, I'm still looking into that. (I've actually printed it out and I'm going to go through it 2night, marking off the ones I didn't think of)
I'm repeating myself about this a lot and I'm sorry for that, but I'm not English speaking and I've got to read stuff you guys write a few time to grasp what you're saying.
My spellchecker is working overtime on this forum as I post!!! ;)
By reading your suggestions quickly, it seems that it's what I'm trying to accomplish exactly.
As soon as I know that I'm doing things the right way with the coding, we can start looking at incorporating more of your very valid points and suggestions.
Because of my ignorance with the coding, I'm not sure if I'm following the right paths? I'll hate to get to the end and have to rewrite the stuff!
As it is at the moment, I'm battling to get the flow of things, although I had to change most of the code I got from other places, they just gave me a general idea of how to do it.
I probably need to make a flow chart of this whole thing and should have done it in the beginning, but I wasn't sure where to start.
If you have done something like this before (with your experience with your work as you mentioned?) can you maybe draw a flowchart of your ideas and tell me where the section I have at the moment would fit in please? A picture tells a....... you know the story! ;)
dubbleUJay (I do know how to spell double though! ::) )
That would be great if Daryl could help WJ with a top down structure for his code. I'm in the midst of new hardware/software checkout for my BBCC project.
I'll check out your schematic within a day or so, WJ. Sure, glad to help you get your values right.
Sorry, guys about some of my heavy handed edits and deletes on the voltage scaler thread. I just whacked anything that I thought was not particularly helpful or was misleading to a later reader, and squashed together some of what would. I need to cut out some of my own posts too, to simplify it, but have been too busy. I'll try to do better. I'm often tactless, and especially when correcting errors, I'm bad.
Quote from: dubbleUJay on December 03, 2009, 09:58:47 AM
Daryl, I haven't forgotten about the things you wrote a few posts ago, I'm still looking into that. (I've actually printed it out and I'm going to go through it 2night, marking off the ones I didn't think of)
I'm repeating myself about this a lot and I'm sorry for that, but I'm not English speaking and I've got to read stuff you guys write a few time to grasp what you're saying.
My spellchecker is working overtime on this forum as I post!!! ;)
By reading your suggestions quickly, it seems that it's what I'm trying to accomplish exactly.
As soon as I know that I'm doing things the right way with the coding, we can start looking at incorporating more of your very valid points and suggestions.
Because of my ignorance with the coding, I'm not sure if I'm following the right paths? I'll hate to get to the end and have to rewrite the stuff!
As it is at the moment, I'm battling to get the flow of things, although I had to change most of the code I got from other places, they just gave me a general idea of how to do it.
I probably need to make a flow chart of this whole thing and should have done it in the beginning, but I wasn't sure where to start.
If you have done something like this before (with your experience with your work as you mentioned?) can you maybe draw a flowchart of your ideas and tell me where the section I have at the moment would fit in please? A picture tells a....... you know the story! ;)
dubbleUJay (I do know how to spell double though! ::) )
Your english is better than most Americans, no joke... And I have to read through the stuff on this list several times too - the information is so condensed it's hard to absorb all of the meaning in one read though.
Yes, a flow chart might be a good idea - but I've been watching and waiting and reading all of the posts to get a good idea of what folks are looking for in this area.
(and I'm not good at drawing stuff - maybe I can find some flowcharting software somewhere... :)
I'm envisioning a master/slave architecture for the whole system.
I'm beginning to think that your choice of the Arduino for the DAQ work is an excellent idea.
The hardware is reasonably inexpensive and has many options for every type of I/O needed. (your Analog multiplexer board is genius - it's just what's needed for this application.)
The software is less impressive, but is simple enough and is extensible enough to do the trick.
The Picaxe software just isn't powerful enough to do this task, IMHO.
(sure you can use compilers and such, but not everyone can afford to buy one and then there is the learning curve and *another* language and IDE to learn)
The Arduino has enough options to act as a "master" that can communicate to the "slaves" that handle different tasks than data acquisition.
The master can collect data that isn't needed for control, and poll the slaves for their respective data and tell them what to do if needed.
I can see Picaxe chips as perfect slaves. They are cheap enough to throw away if you blow one during development work.
(I've found that the 'closer' to the actual hardware any electronics are, the more hardy they need to be to survive in day to day work)
The slaves will do all the actual control work. They will connect to all necessary sensors (and no more, it's a design philosophy) and run all actuators needed.
All of the control code will be in the slave, with just enough extra to talk to the master to transfer it's information (sensor readings, actuator positions, etc.) to the master.
All of this sounds terribly complicated, but you're already contemplating doing most of it.
A mind picture:
You sit at your easychair and hear the lister's exhaust note change - you wonder what caused it.
You walk over to your computer and call up the status screen that's talking to your Arduino and check it out.
The real-time graph of power consumption looks ok, so you switch to the detail screen and see that the hot water heater has just turned on and that you're drawing a little too much power.
You click on the little button on the screen connected to your hot water heater system to shut it down.
It sends a command to the Arduino which says to cut power to the hot water system. It then sends a command to the Picaxe that's controlling the load managment.
It sets one of it's output bits low and the relay drops out.
Meanwhile the Arduino is still scanning it's data points and talking to the two Picaxe systems that control the engine management and load management.
The load management picaxe does it's routine data squirt to the Arduino when polled and the Arduino in turn sends it's info back to the computer in the house.
Which then shows that the water heater relay is off and changes the color of the button you just clicked. And now the power draw is more reasonable and you go back to your coffee...
By breaking the big task down to little pieces the whole system becomes manageable. You can install just a part of it and add more later as needed without having to redesign the entire system.
You can blow a fuse on any one part of the system, and the rest just keep doing what they've been told to do.
This is the way the big boys do it, but again, you don't need to do all or even most of it.
The advantage is an extensible system where you can reuse most of the code. Each section can be changed and reprogrammed without affecting others.
Different people can program different parts and as long as they agree on the protocol for intercommunication they can all play nice together.
Again, it's probably a pipe dream, but it's better to have some kind of framework in mind when you start out on a big project.
So, go ahead and beat me up, I've got big shoulders. ;D
Daryl the Dreamer
Quote from: BruceM on December 03, 2009, 11:38:25 AM
That would be great if Daryl could help WJ with a top down structure for his code. I'm in the midst of new hardware/software checkout for my BBCC project.
I'll check out your schematic within a day or so, WJ. Sure, glad to help you get your values right.
Sorry, guys about some of my heavy handed edits and deletes on the voltage scaler thread. I just whacked anything that I thought was not particularly helpful or was misleading to a later reader, and squashed together some of what would. I need to cut out some of my own posts too, to simplify it, but have been too busy. I'll try to do better. I'm often tactless, and especially when correcting errors, I'm bad.
You do a great job of moderating, BruceM !
I'm a moderator myself, it's a hard job at times trying to balance everything...
Keep it up,
Daryl
Folks,
Another thing I forgot to talk about is isolation.
Almost always when working on several pieces of equipment - engine, generator, pumps, battery bank, inverter, etc. you'll find that there is a voltage difference between them.
Sometimes AC, sometimes DC, most often a mix of both...
This is due to leakages in insulation, corrosion, capacitive induced voltages, magnetic coupling, and all sorts of ways you will have never heard of till you try to get things to talk together.
If you try hooking the grounds together so you can use microprocessor level signals to communicate, you'll find it pretty difficult at times.
You can try all sorts of methods of grounding and isolating your equipment, and still tear your little remaining hair out trying to get rid of noise that interferes with your signal.
If you improperly inter-tie your equipment, you also may get what's called a ground loop - a circulating current between the ground points that can baffle you.
This usually shows up as bad noise on your sensors, although I've seen it so bad that the wires that tied each D/A board to each other to supply a common ground would simply melt for no good reason...
I think you folks were discussing how another guys project kept burning up isolation amps - been there and done that !
BruceM's idea of using opto-isolated RS-232 communications is something that can save your bacon and sanity.
The idea is to let each little Picaxe or Adrundo float at it's own voltage where it's happy, and let an optoisolater take care of the problem.
The signal is carried by a changing *current* rather than a voltage. Most voltage signaling systems are pretty high impedance, which means that it doesn't take much to induce interference.
Now a current loop (as they are called) is a low impedance system - it takes a nearby lightning strike to cause a current loop to fail.
So your output pin of your microprocessor of choice drives a transistor on and off, which switches a 20ma. current on and off.
(this is the industry standard current, this method is used in factories all over the world and has been used for decades due to it's robust nature)
Back at where the signal is going (which can be miles), that 20ma current turns an led on and off, which in turn makes a phototransistor switch a voltage signal into your second micro's I/O pin.
They make nice little four pin IC's that handle everything - optoisolators.
You can easily have a Picaxe sitting at hundreds of volts to ground and still talk to another unit that's grounded or hot in some other fashion.
http://en.wikipedia.org/wiki/Current_loop (http://en.wikipedia.org/wiki/Current_loop)
If you use this type of topology, separate masters and slaves communicating via current loops, you can save yourself time and trouble by having communications that work the first time and don't die every time the humidity gets high in the generator house or battery area.
These are just a few more thoughts on the "DIY Data Acquisition/Engine Controller".
We might not ever need some of these ideas, but being aware of potential problems never hurts.
Daryl
Quote from: BruceM on December 03, 2009, 11:38:25 AM
That would be great if Daryl could help WJ with a top down structure for his code. I'm in the midst of new hardware/software checkout for my BBCC project.
I'll check out your schematic within a day or so, WJ. Sure, glad to help you get your values right.
I'm looking at some flowcharting software right now - I'll be trying to put together a "top down structure" together today or tomorrow (I'm a bit busy myself right now :)
Now where's my paper and pencil...
Daryl
Good that you mentioned opto-isolation, Daryl, and that was a good explanation. I use it for anything with a wire over a few feet. It makes sense to bullet proof a homebrew system; the extra cost is insignificant, an the time savings in not having to "chase gremlins" makes life easier.
For very long runs, hundreds of feet, 10ma is normally plenty, for 2 dozen feet, 2ma works. But I'm always trying to save every ma, as it's all off grid, battery powered. As Daryl says, 20ma current loop is an old standard from back when I was banging a teletype with paper tape.
For example, my Battery bank charge controller (BBCC)has a triple solid state relay for adjusting PV charge current. The schematic link is below. The controller can pick which series PV tap (of 2) as well as a big power resistor. (No PWM crap on MY clean lighting DC.) It's a good case for an opto-isolator, even though only a few feet away, because it's switching up to 210VDC, and any current switching is also glitch inducing...and really should be optically isolated from the processor.
I usually use Panasonic's PC123 opto-isolator. One ma will just operate it with a high impedance ouput, new, so 2ma is a safe minimum drive current. They're cheap, fast, low power. On the PV SS relays, the PC123's drive 1411N's, a micropower mosfet gate drivers.
Similar story (6 total opto-isolated controls total) my AC battery charger; there in addition to 3 of the PC123's for a zero-cross capacitor switcher board I designed, but I also use 3 of the new opto-mos by Panasonic. They are opto-isolators that can switch even 240VAC, up to 150ma, plenty for an AC relay coil. They are really sweet- no EMI like the old, nasty opto-triacs. So for about 3ma of current, you can cleanly switch an AC coil relay or contactor.
Likewise, signals between the well house, where the BBCC resides with the batteries , and the "House of Lister", are 80 feet away, on a separate small PV/battery, and are all opto-isolated. And the signals/serial data to the shop, about 400ft. I use CAT5 cable for the opto-isolated signal; with a current loop on twisted pair, you've got a very solid link, even if you reduce the current drive. The PC123's are about 50 cents each, as I recall.
One last tip before I sign off tonight- I just finished a bench test "fly off" of 7- 500ma and 1A low drop out (LDO) linear regulators; they were all direct pin replacements for a 7805 , 5V regulator. A conventional 7805 will draw as much as 6 or 7 ma even with no load. The current to ground then increases with load. Since the LDO regulators are designed for battery systems, they draw much less; typically between 0.15 and 1 ma, with no load, more with load. It's only important for things that are constantly on, drawing your battery down. LDO's don't have as good regulation, I was not happy with the 0.3mv of noise that was common in many. Some are also unstable with ceramic capacitors (too low ESR for near the regulator).
The hands down winner: ST's LF50AB. It has good regulation, 0.1mv of noise, and is perfectly happy with any capacitance (ceramics OK) on the output. The quiescent current is about 0.5 ma, a good compromise for getting better output regulation.
Wow Daryl, you've given me a lot of info to ponder over a few times! ;)
I would think that we should 1st agree on hardware as you said, I'm biased towards ATmega 'cos I've got one and haven't used PICaxe.
Just a few thing about the Arduino that I've found of interest so far:
1) Some people has taken microSD cards and used that for storage memory.
2) This guy has Arduino nodes&hubs with input onboard- http://news.jeelabs.org/projects/
3) Sensors and Extension Boards- http://www.seeedstudio.com/depot/
There is a lot more on these sites that meets the eye, scratch around a bit, particularly the JeeLabs site!
If one looks hard enough, between the 2 sites one should be able to build a whole home automation system IMHO!
Most of the above is open source & the PCB layouts are available.
The multiplexer inputs can just as well be extended to 4x16=64 analog inputs if we need it!
I 2nd the RS232 comms and there is a Arduino board with a serial port available, although I would rather use 485 for distance, but would that be a problem with opto-coupled connections?
I have at least one application where I need wireless +/-300m, my water-well is across a field from my place.
I've dealt with earth-loops before and know what a pain they can be!
I'll keep myself busy with the sensors in the meantime until we have a direction to agree upon, they should be applicable in any we chose I think. ;)
Wilhelm
http://www.rs485.com/rs485spec.html
WJ,
This should help you understand the various ways to get serial data around.
Optically isolated current loop is a nice solution, as it solves the distant, common ground problem. Lightning in the area causes big shifts in grounds, that fry non-isolated systems. 485 is just differentially driven, not isolated.
I'm looking forward to see what Daryl and you come up with!
Best Wishes,
Bruce
Thank you Bruce, I've used 232 to 485 converters before on CCTV PTZ control to acquire the necessary distance, from there the little knowledge I have on them.
I can visualize this project in my head as I've looked at home automation systems before using the CAN-bus with "Star & Nodes" as in the CARACA project which didn't seem to get to far.
I've got your resistor values for the scaler, WJ. In doing so, I found an error in my prior posted schematic, that I also have on my PCB. I goofed transfering from breadboard to schematic. The difference amp had the + and - inputs backwards.
In addition to that, your schematic for the current amplifier needs a change. The shunt must be in the negative power lead, not the positive. If the load shunt is 0.01 ohm, that would be a 0.3V drop at 30 amps, too much, take a look and see if 0.002-0.005 ohm is available for you. In your diagram R12/R11 sets the gain, we want 30 amps to be 5V. To calculate the voltage drop across the resistor it is just ohms law for 30amps and whatever the shunt resistance you use.
Thank you very much Bruce! Now I can carry on with that 2day ;)
It makes sense about the shunt, I'm reading to "ground". I will find out if a 0.01R shunt is available, I just used the 0.005R is available from RS Online in ZA, I did use one on my schematic. Is 3W OK or should I use a 5W?
Its such a bummer that I have to work around "availability of components", it narrows my scope considerably :(
OK, does this cct look right to you guys?
I worked out that I need a 33 1/3 gain for the current op-amp ???
When setting the voltage on what you show as RV1, the test point should be moved to pin one of the connected voltage follower. You can't read a 1M ohm impedance signal directly with a VOM, and reading it after the voltage follower means any op amp offset error is eliminated.
Another issue to consider; the current sense can be uni-or-bidirectional. In my setup, they are all uni-directional, but if you want to be able to read the sum of charge and discharge only, then bidirectional is the way to go. That just means biasing for 2.5V reading at zero current on a 5V scale.
0.005 ohms will give you a 0.15 volt drop at 30 amps, which is 4.5 watts of heat dissipated. A bit much, but OK if you go with say 15 watt or better shunt resistor. You want your shunt resistor to stay cool, else accuracy will suffer.
YES, you got the gain resistors right; gain for the current amp should be 33: 5v/0.15 V drop at 30 amps with 0.005 shunt resistor, less if you'd like a bit over 30 amps max. 2M/60K is 33, right on.
Makes sense to me for you to stick with the girl you brought to the dance- the AVR chips and their well supported free C compiler are highly regarded, and since you're already Arduino'd (AVR) , and will need to use some AVR C with the Arduino language anyway, you might as well stick with it. I don't know what hardware you need to program the AVR chips, but I'll bet it's not much $.
Quote from: BruceM on December 04, 2009, 07:16:07 AM
When setting the voltage on what you show as RV1, the test point should be moved to pin one of the connected voltage follower. You can't read a 1M ohm impedance signal directly with a VOM, and reading it after the voltage follower means any op amp offset error is eliminated.
I thought there was a mistake on my cct Bruce, thanks.
What confused me was that your original Batt Scaler cct said:
"Set R3 for 3.43V at Ux pin7" Your trimpot is R22 & pin7 is on the spare opamp ???
Quote
Another issue to consider; the current sense can be uni-or-bidirectional. In my setup, they are all uni-directional, but if you want to be able to read the sum of charge and discharge only, then bidirectional is the way to go. That just means biasing for 2.5V reading at zero current on a 5V scale.
0.005 ohms will give you a 0.15 volt drop, which at 30 amps is 4.5 watts of heat dissipated. A bit much, but OK if you go with say 15 watt or better shunt resistor.
For my 1st sensor I'm going to read my 24Vdc 5A Control Battery Charger from my Gen-head. I'll scale it to say 10A and would only need to dissipate 1W5 so my 3W resistor should do. I can see myself battling to find a 15W though!
Quote
Makes sense to me for you to stick with the girl you brought- the AVR chips and their well supported free C compiler are highly regarded, and since you're already Arduino'd (AVR) , and will need to use some AVR C with the Arduino language anyway, you might as well stick with it. I don't know what hardware you need to program the AVR chips, but I'll bet it's not much $.
That's what I thought, I just hope that I can convince Daryl to this idea ;) If I use the AVR nodes with on-board I/O's in the future, I'll be familiar with the language.
The Arduino AVR comes pre-programmed with a boot loader and you can get the chips by themselves with boot-loader installed, from some suppliers.
The board has ISP header on it, but it gets programmed directly with the USB cable at the moment.
I've got the AVR Compiler somewhere, but I never actually used it, the header programmer costs a few $ IIRC.
OK, I'll get the parts for the DC Sensor soon and built it.
O-yes
Bruce, one thing, can I put 5V1 zener protection on the output to the Arduino? I'm worried about a spike if someone short the battery leads for a split second and it draws a huge current that gets transferred to the output ???
Or am I talking rubbish?
WJ- Sorry, I noticed that as usual, my schematic was pretty bad. I don't assign part numbers until I do the PCB layout, and then sometimes I just don't, or get them wrong. I sort it out when building the prototype.
On my voltage scaler, my utterly frustrating memory problems sure showed- I HAD fixed the problem of the +,- input reversal when I did the PCB layout, BUT THEN FORGOT to change the schematic. 5 days later, when double checking the finshed circuit board after receiving it, I newly FOUND THE "error" in the board compared to the not corected schematic, had no recollection of the PCB fix, - and modified it back to WRONG! Now I have to undo the two cuts and jumps.
If you do the voltage/current circuit on regulated 5V, the output CAN'T be over 5V, so there is no spike issue. If it was running on say 12V battery, then you'd use a zener to limit the output from a spike, after the 2K ohm resistor and the reference voltage for the difference amp (subtraction) you'd generate via a micropower adjustable reference.
As for architecture and processor choices, there are plenty of good ways, and I'll encourage anything that can reasonably be expected to succeed.
For my own system, low power was a big priority. I don't always run the generator head but more often the air compressor. So the controller is running off of an old 12V AGM battery (still plenty of capacity for this use, not for it's original) with a 40watt PV panel. I have more experience and didn't have any need to add more processing power. Having designed and built many real time multiprocessing systems, I had no lust for more than the simplest controller that could do the job, and a single 40X1 did it all with no expansion required.
A poky one second frame rate, for example, I thought was totally adequate, and allowed me to use the cpu time chewing count command for rpm sensing, instead of adding a frequency to voltage chip, and reading RPM as an analog value. If I needed more processing power, that's the first thing I'd do. The next would be to use the Boost Basic compiler, which would give me about 10x more speed (which I don't need). And then I can quadruple my speed again by using a 16Mhz resonator instead of the built in 4Mhz.
I don't see anything in your plan so far that I couldn't do with a single 40x2, probably with no expansion. Or a single AVR chip with some expansion, or a few of each, just for fun. And I like the Ar-ar-arduino (multi arduino) too. :) If you have the power budget; "got a task, get another processor" is an approach which can help break things down into more manageable pieces, and as Daryl says, it IS how most big projects that came out on time got done. It allows big teams to separately and independently work on different parts, with well defined interfaces between them.
For anyone who might be interested. My favorite opto-mos part for switching 150ma of up to 240VAC to control an AC relay: AQY214EH. It's a 4 pin dip. $2.11/1 at Digikey.
Quote from: BruceM on December 04, 2009, 02:27:33 PM
For anyone who might be interested. My favorite opto-mos part for switching 150ma of up to 240VAC to control an AC relay: AQY214EH. It's a 4 pin dip. $2.11/1 at Digikey.
I'm taking careful notes of all of these great hardware recommendations !
I've decided to bite the bullet and am in the process of learning the Arduino's version of C.
It takes a lot these days to make me learn a new language, but this forum has lit my fire I guess. :)
I'm *still* trying to get up to speed on all of the topics in this mail list, but I'm making progress.
DubbleUJay - on my previous posts I didn't mean to imply that we needed a mix of Arduino and Picaxe for this application, just that if we set this up correctly, any flavor of micro can be interfaced.
Do you have any plans to do engine control too ? I'm just curious (I'm half cat I think sometimes) as to your further plans.
It might be an idea to come up with a little tiny board that can handle all of the current loop communications.
Something that you could hook up to any random voltage for the powersupply and has an input and output connection to the micro of choice and a current loop out.
It would give a common interface that would be garinteeded to work. If any problems came up you could be sure that it was in your programming, not the hardware.
I like the Jeelabs stuff, but wireless is untrustworthy, IMHO, and would be a lot more expensive than an optoisolator and transistor/fet on a board...
Comments ?
(time to get an Arduino on order too)
Daryl
Glad you found the opto-mos helpful Daryl. I was a happy camper when I found those, originally I could find only 120VAC capable ones by Claire, and my primary AC is all 240. I use one at the end of a few hundred feet of twisted pair form my remote well pump control. They can also be used for DC, some units up to 300 ma load or better, high voltage.
I'd just integrate the opto isolator on the board with whatever other extras and interface are needed for a "slave" processor. The driver might be direct from the processor, or a transistor buffer, or 74HCTmos which can drive 25ma, along with some other buffered outputs. In many cases, you may have a gate or something left over that you can use for the output driver. I suggest avoiding unnecessary segregation- it just adds more wiring, power and hookup, and more points of mechanical failure.
But it does mean planning instead of just building the pieces and cobbling, and for prototyping, I'm for whatever works for you to get the job done at your own pace and style.
Quote from: BruceM on December 04, 2009, 01:09:41 PM
....my utterly frustrating memory problems .....
.....And I like the Ar-ar-arduino (multi arduino) too. :) ...........
Bruce, I cant begin to imagine how frustrating that must be! :'(
The other point: We'll see what Daryl thinks of the idea of using AVR throughout, I'll certainly will go for it obviously ;) I rather like the bare-bone "Arduino" node with I/O's, coupled with your Opto'ed RS232, can't get much simpler than that I think!
;) You still out there Daryl? ;)
Modified: Sorry guys, I posted this and when I hit enter, all of a sudden there was a few posts I didnt see ??? Now to read them! I'll be back ;)
Quote from: Crumpite on December 04, 2009, 04:15:38 PM
I've decided to bite the bullet and am in the process of learning the Arduino's version of C.
It takes a lot these days to make me learn a new language, but this forum has lit my fire I guess. :)
No that's good news Daryl, I was beginning to think I'm the only one that thought this is the way to go.
If you don't already have it, get the "ARDUINO NOTEBOOK" for reference, it has a few basic I/O cct explanations at the end.
http://www.arduino.cc/playground/uploads/Main/arduino_notebook_v1-1.pdf
FYI, I've got the Arduino Duemilanove board, but any should work:
http://arduino.cc/en/Main/ArduinoBoardDuemilanove
Quote
Do you have any plans to do engine control too ? I'm just curious (I'm half cat I think sometimes) as to your further plans.
Yes, but I thought it best to do the Data Logger 1st as a lot of the controllers inputs or variables would be coming from it like over temp, oil pressure, speed exec. The plan for now is to use 1 Arduino to do both if possible, but it can be split in 2.
In the future I have:
Small irrigation system to control
Commercial borehole pump controller with I/O to interface and monitor & control
a "Temporary shelved" wind turbine to monitor
and a few other odds and ends.
So you can see there's a lot of future plans ;)
Quote
It might be an idea to come up with a little tiny board that can handle all of the current loop communications.
That would be great, but we need to also decide if we're going to use "series or parallel" topology? I think just T-ing off from one board to the next would save a lot of wiring, but I don't know what the hardware/software consequences would be?
Quote
I like the Jeelabs stuff, but wireless is untrustworthy, IMHO, and would be a lot more expensive than an optoisolator and transistor/fet on a board...
I also think that wireless should only be used were one really need it. I have one application for it, so I would like that as an option. I was thinking of using the JeeLabs idea with our own comm's on the board.
A few thought on the comm's:
Personalty I would build my own AVR "nodes", but say someone wanted to buy a few off the shelf Arduino's and do this project? He would need an USB/RS232 interface between that and whatever we use.
If we can come up with something that would directly interface with Arduino, it would be nice.
On the other hand, he'll have to build the "network board" anyway ???
Something else as well:
For the analog expansion ports, Seeed Studio does sell a few flavors, but although the code would basically work the same, I don't know what I/O pins they're using, if I knew, I could make mine the same and theirs would be compatible to this project as well?
Soooo many questions!!! We'll get there in the end though ;)
NOW, back at you, any comments? ;)
Bruce, on my DC Voltage probe were you worked out the values of the resistors for the voltage reading.
How critical is the resistor values ie the 327k & 178k? I can make up the one(178k) with 2x resistors, but the other one(327k) will have to use 3x resistors to get the precise value!
Thanks in advance,
With fixed resistors if you lower the gain slightly, you won't "lose" high voltages by having them go to the 5V rail, then you can just measure what you have (ohm meter), and change the software calculation to match those units.
Does the Arduino language and your board support I2C? If so, if needed, a second board could be an I2C slave. That would be a big improvement over asynchronous serial data transfer. I2C is a 400KHz two wire bus that must be short, the second processor would need to be co-located with the first. And of course then either processor could still have an asynchronous serial link to a remote processor.
Thanks Bruce and yes, it does support I2C, although by using a library called wire.h
http://www.neufeld.newton.ks.us/electronics/?p=241
I could have used it for my 16ch expander as well I suppose if you look at the link. I see it can support up to 127 devices!
So this will work for co-processing at the same location. (Short distance)
Do you have any suggestions on using comms over longer distances, but that can be daisy-chained?
Obviously keeping the hardware as simple as possible.
As usual, my networking knowledge is limited, but I should pick it up quickly I hope! :'(
AND, a final question for tonight: ;) (Maybe I'll check-in later if there's sh!t on TV though!)
What programming platform would be popular to write a UI with?
I'm leaning towards Java as I see it getting used all over for Arduino projects, but I dono notin' about programming applications and would like to read up a bit so I don't come forward as a complete idiot once we get to that stage! ;D
If Java is the "thing" anyone know of a free Java System Development Kit for it? I think that's what its called ??? Most seems "website" orientated.
WYSWYG would be nice for a beginner or am I dreamin'?
Yes, the I2C would be a good solution for co-processors, assuming the Arduino code supports both master and slave functions. Study, study!
In order to suggest an appropriate serial link design, I'd have to know what your plans for it are- distances and amount of data, and rate (data block transfer in Hz), and who (which processor) needs to talk to who. You are likely getting carried away, a ring puts a burden of passing along data on every node, and you would more likely have a star or less. Your system is very small, not very complex from what you've described. It's a no-brainer, once you decide what it is you're doing.
I can't offer help with Java or PC GUI suggestions, I have zero experience with them. But I think there might be some guys here who might be able to help WJ in the right direction??? Anyone willing to share their experience and do a little teaching? I'd love to learn about it. GUI's came after my time, and I never worked professionally with PCs.
Best Wishes,
Bruce
Quote from: BruceM on December 05, 2009, 02:16:35 PM
Yes, the I2C would be a good solution for co-processors, assuming the Arduino code supports both master and slave functions. Study, study!
In order to suggest an appropriate serial link design, I'd have to know what your plans for it are- distances and amount of data, and rate (data block transfer in Hz), and who (which processor) needs to talk to who. You are likely getting carried away, a ring puts a burden of passing along data on every node, and you would more likely have a star or less. Your system is very small, not very complex from what you've described. It's a no-brainer, once you decide what it is you're doing.
I can't offer help with Java or PC GUI suggestions, I have zero experience with them. But I think there might be some guys here who might be able to help WJ in the right direction??? Anyone willing to share their experience and do a little teaching? I'd love to learn about it. GUI's came after my time, and I never worked professionally with PCs.
Best Wishes,
Bruce
Folks,
I agree with Bruce (again!) - any type of topology that has multiple receivers/transmitters on the same buss can get *very*complicated in a hurry. (look at Ethernet !)
What you save in wire is more than made up in loss of hair and the cost of faster/more powerful micros to handle all of the overhead.
It would likely eliminate the possibility of using Picaxe's except for the most powerful ones.
I've done a fair bit of work on GUI's but always with a proprietary language, which doesn't help here any except in the most general terms.
Java seems to be the popular language, but I don't know a thing about it either. (another language to learn - arrgh...)
However I hear that it's based on the C language, so it should be similar to the Arduno language...
There do appear to be lots of examples of Arduino/PC communications out there, which will help a lot.
I've got my Arduino Duemilanove and a few other tidbits on the way, so I should be up to speed in a year or so. :)
dubbleUJay, I already downloaded the manual you pointed me to and gone through it - it's a nice little starting place.
Well, back to the salt mines...
Daryl
Guys, here's a couple of thoughts as I see this project further down the line:
My DataLogger/Controller we're busy with is just one of the "nodes" of a modular system.
If we use the same micro, hardware, programming language and interconnecting structure, anyone can design a module and put it on the overall system.
Most of the nodes will probably only have a few inputs for data logging and maybe 1&2 outputs to switch something on/off.
I can name a few modules just of the top of my head:
Solar array data logging
Wind turbine logger
Water pump control
Simple irrigation system
exec. exec.
Lets say that the furthest module would be 100m away from the main controller/PC, after that I'll go with a wireless link.
Now for a biggish module like the Engine logger/controller a full blown Arduino make sense, but for most of the other a bare-bones-board would do. (A Kit cost about $12)
As long as they all connect to a central hub/PC in the same manner or talk the same language for that matter.
We have the option of incorporating a SD Memory Card for storage on each module as well, but I don't know how viable that would be. Maybe a single Arduino hub (with storage) were to all the modules connect to as a front-end would do ??? (Daryl, I think this it what you meant a few posts back)
Most of this data can be sent to the central controller anytime within reason if "decision making" is done within each module like Daryl suggested.
Now what type/speed of comms we need to accomplish this, I don't know ???
We have to consider that a PC would not be on the whole time as well.
I'm probably missing a couple of point here as well. :'(
I've included a few pictures and info on some available boards like bare-bone & Serial interfaces just to get an idea of things, in the attached PDF.
A couple thoughts- First, thanks Daryl, you are much appreciated!
WJ, sure, a distant data collection situation cries out for a processor with a serial link. At 100M I would recommend plastic optical fiber (Industrial Fiber Optics stuff is cheap and works great), if you want lighting proof, else the opto-isolated current loop on impedance matched twisted pair.
I'm using a I2C flash memory chip in my battery bank controller for battery charge cycle data logging. A little 8 pin dip with 1 Mbit of space for $3. It's just dip socketed so I can pull a tab and swap it out for data retrieval (Picaxe chip as reader using serial to USB link to PC), or use the slow, 600 baud opto-isolated current loop serial data link down to my shop located computer for just pulling the most recent time stamped records.
I'll bet there's some nice Arduino board with a memory stick or flash memory card of some kind, if you've got the power and $.
I'm not sold on the boards, though it is a tough choice given the Arduino bargains- I always need some analog and digital "glue" chips, so if I'm making a board, I'd rather just put the processor on it and do one board with less connectors, and I get just what I want, instead of tacking on a second board to what someone else thought I'd want.
Bruce, I'm quite happy with twisted pair and I'll use that in most of the applications, but what I dont know is how would one switch between the different modules from the PC side of things?
I've only dealt with 1to1 comms.
The multi-systems I worked with i.e. PTZ control and addressable fire alarm equipment all had dedicated equipment controlling them, so I'm kind of lost on this one.
I presume that each module will have some type of address to be able to communicate with them individually?
Or maybe I'm missing the point here guys ???
Folks,
DubbleUJay,
I'm envisioning this type of network:
First you have a Master. It's the first board you install in the system.
It has some sort of connection to your PC, whatever flavor you'd like.
It's only task in a properly designed system (which we may take liberties with) is to collect and store data and handle all of the communications with the PC and the Slaves.
It also has the higher level code for controlling the Slaves. (see below...)
The Master will need a serial com port for each slave and some kind of com link to the PC.
This may limit it's usefulness as a data collection device. (in which case we just add another slave node to do the data collection)
The PC has two functions, first to download data from the Master and display and/or store it.
Second, it can send commands to the Master, anything from "dump me your data" to "send a shutdown command to the engine controller."
There can be Slave boards connected to the Master. They do only two things: they collect data and store it only long enough to make decisions on, and send to the Master.
They also do all of the actual control of the system - they have outputs that control things and the code to do it.
This system has many advantages: the Slaves can be simple, low cost units. All they need are inputs, outputs, the control code and the communications code.
If needed they can do a little data reduction and short term storage, but only enough to get by.
This means the program is pretty simple, and the communications code can be reused from Slave to Slave.
Also, the Slave should control only one device, like the engine, or battery management, or wind turbine.
The Master contains the higher level code that coordinates between the slaves.
If the battery management Slave says the battery bank is full, the Master sees that in the data and it's control code sends a shutdown signal to the engine Slave.
(or whatever)
It has the potentially expensive storage system, and communications link to the PC.
Each subsystem can work without the others there.
If a mouse nibbles through your wire out to the engine shed, the engine continues to run and is still protected by it's separate controller.
You just loose the data that was being sent, and the ability to control that subsystem. So you walk out there and hit the shutdown button manually.
(and find the break in the cable !)
Of course you knew about the cable break because the Master noticed that there was no communications and sounded some sort of alarm !
Bruce,
I know what you're saying about the boards. It's much more expensive to buy general purpose boards, plug them together and add your own interface.
But part of the idea here is to make this thing usable and less intimidating to fledgling CHP folks. :)
However, with all of the schematics and Eagle files out there for the Adrundo system, it would be simple to make up our own version of "CHPundo" or whatever. :)
Got to run,
Daryl
Now Daryl, WHY could I not put it like that into words ??? ;)
That's about the way I envisioned it!
Another nice thing about this way is if a guy just want an engine controller, he can just get/buy that hardware for the module, load the code into it and he has a stand-alone version, which, if we play our cards correctly, could still plug into the same port as the main controller would have to the PC and get control via it. (I think???)
I don't want to jump the gun, but we should be able to do the controller with an Arduino as well if the following might work?
1) SD card & USB sticks has already been done with the Arduino, although it uses a lot of code apparently, unless one uses a "smart" reader for them with real-time clock, UART/SPI interfaces exec.
(I've got to look into this more, but here is a link to one: http://www.sparkfun.com/commerce/product_info.php?products_id=8215 )
2) The 4067 that Bruce suggested is a 16ch Mux-/Demux which probably comes in a digital form somewhere? Without looking back to Bruce's optical-232 (2wire or 4wire ?) The code to control 2or4 of them to switch the wires between modules should not be difficult or huge. That's if one can switch 232 with them, I don't know if its fast/good enough?
I'm calling it a day!
WJ
If you are going to expand the remote master-slave star extensively, to say 8 slave nodes, for fun or whatever, then you can use cmos digital mux/demux chips (not analog switches) for the master to select the appropriate slave. One output, one input per slave for asynchronous serial data. (Two pair- or a single pair if half duplex.)
If you have lots of processors that are in the same room (relatively short distance but you don't want to co-locate and use I2C bus), then busing the serial lines between them is a solution. Depending on the data rates, this could even be half duplex, a single wire with pull ups, open collector drivers, data packet id headers (just a byte) to tell which slave's data it is) will simplify the hardware. Each slave on the bus does have to read every data packet to determine if it's "his", and data packet integrity must be checked, which is overhead you'd like to avoid unless it makes sense for the system overall. If I2C is used with a chip that does in hardware, like the Picaxe X2's that overhead becomes relatively transparent to your processor.
It's all largely a beer fart until you define the actual data, rates, and distances, at least as a preliminary estimate. Planning expansion capability is good, but keeping things practical and simple helps others who might like to use it, too.
Great, thoughtful comments on the design and Arduino hardware use, Daryl. Applying the Arduino stuff that's out there well is a good idea. I'm biased towards greater simplicity and am more of a roll my own type, but appreciate the value of the use of the Arduino gear for an "open" project.
Quote from: BruceM on December 06, 2009, 10:25:33 AM
If you are going to expand the remote master-slave star extensively, to say 8 slave nodes, for fun or whatever, then you can use cmos digital mux/demux chips (not analog switches) for the master to select the appropriate slave. One output, one input per slave for asynchronous serial data. (Two pair- or a single pair if half duplex.)
Thank you Bruce, I've got a feeling that this might be the way to go. I'm thinking if one are going to use a Master Module it might as well have at least 8 I/O comm ports for future expansion.
Quote
If you have lots of processors that are in the same room...............
IMHO this will probably be the exception to the rule, in my case anyway. The only place I can think of right now where I'll use 2 is if I split the Logger/Controller, but there will be other instances.
Quote
It's all largely a beer fart until you define the actual data, rates, and distances, at least as a preliminary estimate. Planning expansion capability is good, but keeping things practical and simple helps others who might like to use it, too.
You guys are much more clued-up on this than me, but maybe the Engine Logger/Controller would give a good indication of what to expect, at least I now know that it should do as much of the calculations and decision making by itself.
Quote
I'm biased towards greater simplicity and am more of a roll my own type, ..............
You wouldn't be an EE if you weren't Bruce ;) You probably saw that I would rather also build my own sensors & stuff, but I keep on thinking of the next guy! I would love for more people to maybe build this thing when its finish, everyone that has one of these would be able to quote some darn accurate figures I would think, while also using it for something useful like control???
This is wishful thinking, but there are even guys logging there data to a communal web-page, like power used, rainfall, wind-speed exec., the stuff one can do is mind-boggling, for me anyway! :o
Imagine Daryl phoning you and saying that he saw on the website that your wind generator's output is 3kW in 30km/h winds, how-u-do-that?
Probably not in my lifetime though! :(
You're doing a great job, WJ. We'll Arduino the heck out of it.
When you get a chance, make a list of your full system (including noted dreams) functions, list of subsystems, and the rough distances between them. We can then discuss the data and data rates. Then Daryl and I can help you turn that into a preliminary spec and communications design that will be ready to do everything you might need, simply and reliably.
Thanks Bruce, Daryl has thrown the stone in the pond and we might as well do it all the way! Within reason obviously. I believe this is where it would have lead to eventually anyway.
I also believe Daryl is busy with some type of flow chart as far as I know? Daryl ???
We can take it from there and add/agree about things?
Hope you recover soon! :'(
dubbleUJay
PS- I've got a hidden agenda, "Arduino" the sh!t out of National Instruments over-priced student edition hardware/software ;)
Quote from: Crumpite on December 06, 2009, 08:33:56 AM
.................. CHP folks. :) .................the Adrundo system, it would be simple to make up our own version of "CHPundo" or whatever. :)
Daryl
I'm getting carried away again, but maybe
"McGuino"Not as in "
McCreary" or "
MacGuyver", but as in "
Micro Co-Gen"! ::)
dubbleUJay (just foolin' around ;))
Folks,
Well right now I'm studying the heck out of ways to do the whole PC/Master control scheme... Argh... My eyeballs hurt...
There is *so* many solutions to the problem it boggles the mind. None of them so far seem to be what we're looking for.
I've got another book to go through tonight, perhaps it will have a few clues as to how to do it.
So far I'm leaning towards some form of visual basic, but that will likely change 17 times in the next several days.
I wish I had more time to put in on this research - I'm commented to helping some friends out with an instrument problem, and it's taking a lot longer than I thought it would.
/rant mode on/
There are so many competing languages, non of which are aimed at what we want to do. So much web development "junk"...
Well, I consider it junk at least. I can do without all of this flash and dazzle on the screens these days.
What ever happened to "form follows function ?"
/rant mode off/
Well, back to the salt mines, my PDF is just about ready to be downloaded into my ebook reader for my bedtime enjoyment !
Daryl
Daryl, on the master hardware side, Bruce has given me a sort of thumbs-up on using my multiplexer idea to switch between the various slaves. He made a suggestion on IC's to use, although he said he's still looking for one that might work better.
I'll draw up something "alpha" 2day to look at.
Do you have any cct from him about his opto-RS232 links? I need to see how many "wires" needs to be switched for each slave?
perhaps i am taking a simplistic approach to automation, basically because of my experience in
the mid/heavy duty trucks and also some of the plc's used in industrial climates.
personally i see little to no need for a ton of data logging, and what little i see the need for can be done
with simple setting of error codes, which can be done with a few line driven led's. give me three lines and i can
give you 9 possible error codes add another line and you can have 16 and so on. if i need more i suppose i could use
a multiplexer/demultiplexer to come up with tons of possible codes.
when you look at a computer controlled automotive application the controls that are used are numerous, everything
from manifold pressure, fuel pressure, oil, water, on and on and on. none of them require a pc screen or human intervention
to operate just fine, and when human intervention is needed you can get into the puter with a 20 dollar code reader and a code
book to find out what the issue is.
now this is not to say that having it all on a puter screen would not be cool, actually it would be very cool, however
it adds another layer of complexity that we will find will come back to haunt you big time.
as an example, i work on cnc controlled component saws in the truss industry, you got the plc's doing the control, and you have
a remote pc and screen to setup the job, calibrate the machine, run the job and display it all. and you have tons of communication
cables all of which become very finicky over time, creating issues that drive you out of your mind trying to sort out.
bear in mind these are all hardened industrial computers, and almost every one i am aware of has numerous major failures and problems before the one year warrantee is out, and it does not improve with age after warrantee.
in my view, plc control has proven to be very reliable and anything we build that emulates their design is a step in the right direction.
now most plc's use ladder logic (relay logic) however there is no reason that other languages could not be used for our purposes.
its not the programming that fails down the road, rather the hardware and implimentation of that hardware.
successful designs seem to have the master and its slaves mounted in a common chassis, this allows for a high quality buss
without lengthy cables and connectors to degrade from various outside problems.
basically what i am saying is in my opinion any successful system should not integrate both data aquisition/logging and automation
they should be as seperate as is practical, the automation system should be rock solid, simple, redundant where possible, and fail to safe
mode, with an operator override capability or manual control system overlay.
the data logging or aquisition system can then be any flavor you like, and can be as ruggedized as one feels necessary or can afford
weighing out the various factors and realizing that probably after a few weeks of oogling the screen, the thing will likely never be looked at again, at least with any regularity, so its need to be nasa quality is probably not necessary.
fault codes should be integrated into the automation control system, only because it would be easier, and because a fault is something
we will certainly always want to know about, even after the new wears off.
my concern is otherwise we end up with an integrated system that is the "jack of all trades and master of none" and likely will be finicky
and suffer all sorts of breakdowns and other anomolies that will be very hard to diagnose.
a couple years back i took on the reverse engineering of the automation direct dl305 plc system, it took me about a week or two to reverse engineer one of the 16pt output modules, another week or so to reverse engineer the backplane, and more time for input modules and i decided to forego the processor module because i knew i wanted to replace it with a micro processor that i could program
in pbasic.
yes i was warned and ridiculed by all the plc guys, got blasted by the folks over at automation direct for hacking their product, but
i learned a ton about proper design and how simple it can be if we use a wide buss rather than getting cute with I2C or other communications protocols,,, we don't need those communication protocols "if" we keep things close, such as in the same chassis
and use whatever extensions architecture to connect to the outside world.
we use 5 volt logic, plc's use other voltages that are much higher and there is no reason we can't use any voltage logic we want
to get from a controlled object and our controller.
the bottom line i decided to learn how things are controlled by the plc guys, also learn how the microcontroller guys do their thing
and then blend the two technologies with available hardware.
its hard for me to want to have pc boards made, source all the discrete components, learn more languages to program different
processors, and basically have to reinvent every wheel on this project along with the spare wheel in the trunk. when just about ever
bit of the hardware is available for a very low cost, one just has to think seriously what he wants to accomplish, lay out a flowchart, then
assemble the hardware to enable control, leaving programming to tie it all together.
but what do i know?
nothing more than how i plan on getting the job done!
:)
bob g
Bob, just for my own info, could you give me some suggestions on PLC controllers that your talking about?
I did look at them a long time ago and the ones I could get over-here in ZA were very expensive AND you then had to buy their software on top of that! :( It might be that I'm in a 3rd world county though and we're just getting ripped off. >:(
IIRC I could get modules and put it all together with a CAN-bus, but I had to have a NASA budget or be one of our Government Officials. (Which seems to have an endless supply of our money, but cannot subsidize my solar hot-water geyser) ;)
In my case, all the hardware in one place wont work:
My well is 300m away
Orchard about 50m
Engine room 20m
Future wind-generator 200m
Weather station 10m
Main DB of house 30m
To name a few just off the top of my head.
I'll be using the weather station and WVO engine data a lot I expect.
The idea with the Arduino is to have the same Master/Slave controllers/loggers hardware throughout, only the software in each one changes and all capable of running on their own and not influencing one another if breakdown should occur. If my engine controller smokes, I'll take the one from my weather station, download the controller software into it and there we go! Until I can get a new one.
There are instances were hardware might not be available commercially like the interconnection scheme we're working on now, but we should keep that down to a minimum if possible.
dubbleUJay
DubJ:
the plc's are as you say very expensive even here in the USA, and yes most have very expensive propreitary software
to program them.
i bought the dl305 and all the related modules off ebay for pennies on the dollar, figureing i would eventually find the software
as well for a good price,
i had already gotten started with microcontrollers, and found that the input and output modules to be very interesting in that
they already were built using the same stuff we need anyway, things like opto isolation is standard fair as are solid state relays
multiplexers and demultiplexers etc, all in nice neat modules that plug into a chassis with a ready made backplane.
i then decided to reverse engineer an output module and then to integrate a daughter board so that i could take control of that
module and in doing so make it a slave, then came replaceing the oem processor module with another micro and make it my master
in the end i decided to move away from this approach not because of anything other than i wanted a bit more room to work, and
because you cannot get a schematic from "any" plc manufacture, it just made sense to take the daughterboard and attach it to a relay
board which could provide my relay isolated outputs and which were ttl logic driven and used a 8 x darlington pair driver to buffer between the relays and the micro controller basically useing the same basic methodology of the plc save for opto isolation.
now looking at what you have in mind and the distances envolved, perhaps you will need to do some other communication protocol
and have widely spaced slaves running off the master? i guess that makes sense
to me it just made more sense to find a way to get all the processors (master and slaves) in one rack mount case, and then go from there to each remote site via cable running a higher voltage logic such as 12, 24 or now maybe 48volts.
i think i can sort out the logic over distance easier than using remote slaves and having to use wireless or some other communication protocol
the advantage to not having remote mounted processors makes a manual override centrally located much easier to accomplish in my thinking, certainly we can have manual overrides at each controlled component, but not having to walk out to take manual control might
make the difference in either my survival or that of the controlled piece of equipment.
i too have about 200 ft to get to my planned windgenerator location, everything else will be within a max of 25ft or so, and most
will be under 10 ft from the automation unit.
i am relatively new to programming, only having gotten into it about 2.5 years ago, but am no newbie to relay logic having had to use
that method for 35 or more years, so my approach was probably based on my background, where i look to do things mechanically first, electrically second, and electronically third, with programmable only after i have thought out the system very well to start with.
this whole topic is quite fascinating to me, and very interesting to see the various methods different folks use or approaches taken
to get basically the same result.
i guess it all comes down to what your comfortable with?
as an example
in trucks much like cars, for the last 75 years or so the heater motor had maybe 3 speeds, it used a 3 position switch and a
resistor block in the heater duct to regulate and dc brush type motor. the cost of the motor might be 20 bucks
today, for some reason engineers think that drivers need an infinitely variable speed motor, in order to accomplish this they attach
a small puter box, microcontroller inside, generates a pwm and drives an H bridge or somesuch to give the driver ultimate control
over the blower motor,, cost for this motor is 250 bucks.
for me, all i need is the 20 dollar system, yes the 250 dollar system would be nice, but not something that is needed by me.
basically this is my design philosophy, use technology where it is a benefit, but use it sparingly.
bob g
Hi Bob, it seems that you have most of the stuff already to make your own controller so that will be the way to go IMHO.
I think I mentioned to you b4 that I'm also fond of electro-mechanical switching, I worked in an British MU telephone exchange for about 10 years, all the flavor of relays you would find, ie slow-to-operate, slow-to-release, high-speed, thermal, you name, the exchange had it. Also motor uni-selectors & stepper-switches.
I use to adjust this stuff, every relay had specific spring tension, armature air-gap exec. exec. One thing I regret is not keeping my toolbox as it had some very weird looking stuff in it for the uninformed. Great stuff to talk and show off! ;)
Fault finding was a blast, "Routiners" were equipment that made call during the night through the exchange and recorded faults it found.
There was a big mainframe computer, no screen, printout on paper only, that did some of the call routing! This thing was huge, used bead-memory!
When they were replaced by electronic exchanges I went over to the Access Control, Fire- & Security Alarm, CCTV department and then onto Microwave Construction, building outstations on mountain tops! ;)
Now me & my brother run a mobile crane business, what a change of scenery!
The good old days!
dubbleUJay
Folks,
Moble_bob,
My background in in industrial automation - chemical plants, water plants, waste treatment, etc, etc, etc.
So I know where you're coming from !
I've worked with relay logic, PLC's and industrial automation computers of many different flavors.
I started out as an engineering tech, became a journeyman instrument man, and finally an engineer.
So I've got experience all the way from an operator of the equipment, to maintaining it, to designing it.
(not trying to brag, just trying to show my history...)
I've been programing since early collage days and built my first S-100 buss computer from a kit.
As for data logging - I personally don't need much, I'm just looking for things like Kw-hours, total run time, water temps, simple stuff like that.
And I likely won't need most of it after I learn how the system operates - but I will need at least some.
There does seem to be a mania about logging everything under the sun these days.
But if I need to do some logging, it makes sense to make the whole system extensible so folks can add to it and log whatever they want.
Nothing is set in stone at the moment - if you have ideas let us know !
I agree wholeheartedly about keeping logging and control totally separate and making the controller as robust as possible.
That's one of the reasons I've been thinking about using a Picaxe for control - they are just big enough to do the job and are proven to be very hearty.
From what I've read on different forums, not many folks know or implement fail-safe design and practice. :(
On the other hand, I just noticed an Adrundo for sale that has been hardened for industrial use. :)
I also agree with the idiot light idea - I included it in my origional list of possible I/O's for the controller.
They sure make troubleshooting a *lot* easier.
"basically what i am saying is in my opinion any successful system should not integrate both data aquisition/logging and automation
they should be as seperate as is practical, the automation system should be rock solid, simple, redundant where possible, and fail to safe
mode, with an operator override capability or manual control system overlay."
Now here you've hit the nail on the head - This is what I'm trying to design into the system !
And that's why all of this theoretical stuff right now.
I've found that if you get the top layer of the system design down pat first, the actual hardware and programming fall into place a lot easier.
On the largest project I ever worked on, I spent the better part of a summer just wandering around in my back yard muttering to my self, when I wasn't sitting at my desk doodling little flowcharts.
Ordering the hardware and the actual programming went pretty easy after that. :)
its hard for me to want to have pc boards made, source all the discrete components, learn more languages to program different
processors, and basically have to reinvent every wheel on this project along with the spare wheel in the trunk. when just about ever
bit of the hardware is available for a very low cost, one just has to think seriously what he wants to accomplish, lay out a flowchart, then
assemble the hardware to enable control, leaving programming to tie it all together.
Again, that's what we're trying to do. :)
The problem is the overabundance of platforms, shields, boards, languages, etc... so much to sort through !
We're trying to design a "system" that can accommodate a lot of different approaches to hardware but still have as much in common as possible.
That's whats so difficult !
Please excuse the debris from the construction project - well get all of this mess cleaned up as soon as possible. :)
Hope this clears up a few points.
Now where was the last book I was reading on interactive programming...
Daryl
Quote from: dubbleUJay on December 07, 2009, 08:33:34 PM
Daryl, on the master hardware side, Bruce has given me a sort of thumbs-up on using my multiplexer idea to switch between the various slaves. He made a suggestion on IC's to use, although he said he's still looking for one that might work better.
I'll draw up something "alpha" 2day to look at.
Do you have any cct from him about his opto-RS232 links? I need to see how many "wires" needs to be switched for each slave?
No, I haven't seen his circuit yet, but might be able to reconstruct it from his description and suggested parts.
You *should* be able to do it with one I/O pin, but I'll need to think on it for a while - two pin's would be easier on the hardware.
We need to drive an LED to transmit and use a phototransistor or photomosfet changing conductive state for receiving.
I'm a bit overloaded with stuff to do at the moment, but will get it it "real soon now"... :)
Daryl
Guys, its been a while since I've givin' any update on this project, but believe me we're busy in the background with some awesome stuff!
It's just that this thread is getting sooo looong and we decided to do a bit of the nitty-gritty work "behind your back!" ;)
As soon as I have something interesting to post or report I'll do so immediately!
In the meantime, its stuff like this in the link that keeps me going!
http://www.windmillsoft.com/acatalog/A000_1.html
What the h*** were they thinking when they slapped the price tags on those! ??? At least for that cost they could have put it in a box that does not look like a nice DIY job and upgrade the software cosmetically so it doesn't represent a win95 app while recommending it for WinXP IMHO!
dubbleUJay
DubJ:
i gotta agree with you on this one, why build something that costs that much and not make it look at least
presentable?
this is where manufactures could take a que from "outback" wherein they have that nice art deco thing going on.
you have a nice case and a product that just works, and folks will never question much else.
this was a part of system design that held me up for over a year on my thinking, there were certainly more expedient
means to house all the electronics, but i wanted something presentable when complete.
however, a comeplete system based on "steampunk" as a theme would be fantastic.
lots of huge bakelite meters with ornate scrolled needles old english numbering for starters would be pretty cool.
or go to the other end of the spectrum and make the engine room like Scotty's engine room on the enterprise?
just seems like "why not have some fun with it"?
bob g
Insidently Jens, the same guys I shot down in my post above claims the free version of their software, (its actually their old version 4, the new version is 6) can monitor almost any RS-232 data sent to the port and represent it to an Excel spreadsheet.
I downloaded the software, but haven't played with it at all. I presume if they say Excel, they mean a comma delimiter file?? (They want your email before you can DL though!) >:(
Once you have that, I can maybe help you to display it as graphs in Kst or Excel for that matter, in real-time and I'm sure Open Office's flavor of spreadsheets can do it as well, I just haven't tried it.
So, the first thing to do is to try and write the RS232 data to file on the PC, that's the difficult part to get setup IMHO.
One tip from me, if you get funny characters in your file, make sure the Baud-rates are the same for the PC-port, your recorder and software.
I hope this might be of help, its so nice to be able to see data on a graph, being it in real-time or not!
Jens, as I understand it, the software reads the incoming data from the RS232 port and write it to a file on the PC.
The port driver is also important and the same guys have a driver for download as well if I read it correctly.
I've got no means of testing it at the moment, but this is how I got the Arduino to work:
Obviously the monitor/controller must sent the data to the 232 port in a readable manner.
My Arduino use a USB port, but the driver for the port "fools" the PC into thinking it has a extra Serial Port installed. Your monitor probably has a straight serial connection I presume.
I've got a 3rd party program that write the data coming from the port, to file. I can chose a file and format and its actually just a TXT file.
The software looks for a pre-programmed string from the controller(Arduino in this case) that tells it to log that specific data. (This is why this program wouldn't work for you as I don't think you can program your monitor to send specific string to the serial port, but I think the Windmill 4 software can as it should prind all data to file)
That data in the file I then link or import to graphing software, also 3rd party and nothing to do with Arduino itself.
You'll have to 1st try and establish a connection with your monitor and look at the data it sends, then take it from there how you're going to represent it.
Jens, some good news, I quickly installed the Windmill 4 software and after playing around a bit, I was able to monitor the data from my Arduino via the USB port and print it to file!!
Its a bit confusing to set it up, looks like Win95 applications and you have to setup various modules of the program itself, but it works.
I suggest reading the manual to find the correct way to set it up. I was just poking around with it.
If it can do this for me, it surely can log your data???
I see a lot of help files on the site itself.
dubbleUJay
PS- I might still swallow my words in my 1st post 2day, but still, its very expensive 134 Pounds IIRC for the software alone and the ver6 doesn't look much different!
Foegot to say I'm using WinXP SP3!
Quote from: Jens on December 12, 2009, 01:01:09 PM
Holy cow, I just looked at the windmill software ... talk about nickle and diming you to death. That is absurd !
What software do you use that just writes the data to a txt file?
Edit: Are you using the gobetwieno (or whatever) software you mentioned at the beginning of this thread ?
Jens
Jens, I didn't know it runs your own code, then Gobetwino would work.
It monitors for a start string like this:(In this case the "LM35TEMPS" is the name of the Gobetwino command you setup in the program itself)
Serial.print("#S|LM35TEMPS|["); The ASCII between the two " "
and it prints to file whatever is between that string and the following "end" string.
Serial.println("]#");
You can also chose to time stamp it.
My LOG file then looks like this:
2009/12/03 19:08:40; 17; 0; 0; 0; 0; 0;
2009/12/03 19:08:41; 17; 0; 0; 0; 0; 0;
2009/12/03 19:08:42; 17; 0; 0; 0; 0; 0;
2009/12/03 19:08:43; 17; 0; 0; 0; 0; 0;
exec., exec.!
This is 6x LM35 temperatures that it monitored, only one connected to the 1st channel at 17degC, the rest are pulled down to "zero"
I've used semi-colons for separators, but you can use TAB or whatever.
Again, the Gobetweno Help file or more so the examples in it, is of great help. It can also email and "print" to a web server, but I haven't used those yet!
This file you then link to graphing software.
Kst seems very nice and widely used, but it crashes on me occasionally, a bad one too, my PC freezes and I've got to hard reboot! :'( I think its something with my PC though, just haven't pinpointed it yet!
That's how I discovered Excel2007 works just as well. ;D
Now I'm sure you'll come right! ;)
Its nice to discover with just a bit of free software that one can do something that you could have done a long time ago, I surely was, I just didn't know how to do it.
dubbleUJay
Folks,
I'm starting to look at programming a GUI (graphical user interface) for this project.
The big question is: what to you want to be able to do ?
Get you needs and wants together now before I decide to start designing the whole mess !!! :)
It might be too late after I nail the design down.
I can see data logging and graphing, but what else ??
Daryl
My controlling embedded processor system is already built, and I am doing that software myself, but I would like to steal this project's PC GUI for interacting with my Battery Bank Charge Controller/power management. It will have an modest speed serial data link to the PC.
I need to be able to display specific data, and set different control parameters, and download for display my logged battery charge tracking info. (So I can watch for a battery that is getting weak.) An example would be to send a 5 day weather forecast to the BBCC, a simplified form so that it can minimize generator use, by anticipating a sunny day or wind. And monitor net power from wind, PV, generator, load. Or other special modes of operation, like top off the battery bank with generator, now.
Daryl, the ability to switch digital outputs on/off and maybe to control an analog output for PWM like a slide or knob.
If there's an option to store incoming data in a log-file as its coming in, it might be used for something else at a later stage if the UI cannot do something we didn't think of now? Kind of like what gobetwino is doing.
Digital & Analog "meter" display would be a great attraction, but only cosmetically though.
Maybe the things BruceM wants can be sent to the controller via small "scripts" ???
I'll have to think some more on this ;)
Don't worry about my requirements much, I can just hard code my PC display/control code; it's often easier than trying to learn someone else's software that does "all the work for you". I'm happy to keep it simple, no fancy graphics or GUI is important for me, I'm happy to just have something simple and functional.
If I find that I can rip off a bunch of the project GUI software, that would be icing on the cake.
BruceM
Gentleman, this post is an update to where this project is heading to at this moment.
I've asked Bruce (BruceM) & Daryl (Crumpite) to amend this specific post as not to have a long discussion/posts about probable faults exec.
For now, Daryl is writing the User Interface for the PC side of thing, Bruce & myself are keeping us busy with the electronics, with help from Daryl as well.
Lets call it a short WIKI-post if I may! ;) I've taken the important parts of email correspondence between the three of us over the last few weeks and put it in this post.
This project has now escalated and it's heading in a different direction as first intended and IMHO, I think it is to the benefit of all people looking for Data Acquisition and Controllers.
Please note that this project is not finalized and there are still a lot of work to be done, but the fundamentals are more or less set, well, sort of!(Names and such for the project and components are just thumb-sucks by me and can be changed as seen fit.)
µCogen Data Acquisition & Controller System (McGuino or µCoguino ;))
1st a Proposed System Layout for clarity:(http://stashbox.org/741920/%B5Coguino%20System%20Layout%20v2.4.jpg)
IMG place holder (I need to draw a diagram for some Slave Examples)
A list of priorities from Daryl:1. Everything to be easily available.
2. Off the shelf if possible, PCB files available if not.
3. Robust mechanically and electrically.
4. Expandable.
5. Inexpensive.
6. Programmable to suit the user.
And, the order above doesn't matter...
PC User Interface program requirements from Daryl:1. Receive real time data from the Master/Slave
2. Receive logged data from the Master/Slave
2. Log data to a file
3. Graph it
4. Send commands out to the Master/Slave
5. Send commands to the Master/Slave at a certain time.
6. Receive requests from the Master.
7. Blow a horn when an error condition happens.
8. Some method to select which Slave to talk to.
He will be using the Python language.
It is the intention that the UI will be able to work to just one Slave (1to1 operation) for those that need just a single system or to many via the Hub Mux Controller up to 8x Slave units.
As stated above, we would like of the shelf hardware where possible, but something like the Multiplexer Hub Switcher will have to be made at this stage if one want more than 1 Slave! :'(
Bruce & myself has come up with a few Slave units I/we might need:(And some of your suggestions, thx)
(I cannot get the "Insert Table" function to work properly)
Wind GeneratorVolt Analog
Amp Analog
RPM Analog/Digital
Borehole Pump3x Status LEDs Digital Existing dedicated control
On/Off Digital
IrrigationOn/Off Digital Timer controlled
4x Moisture Sensor Analog
Mains PowerVolt Analog/Digital
Amp Analog/Digital
Meter "tick" Digital Utility meter 1000imp/kWh
Battery Controller Volts
Amps-IN
Amps-OUT
Engine ControllerThrottle Control
Emergency shutdown
Idiot Lights
Engine Data Logging 6x Temperatures (<125C)
2x Exhaust Temps (High)
RPM
Fuel Flow
Low oil pressure
Aux digital Inputs
Weather Station Wind Speed
Wind direction
Rain Meter
Humidity
The otpo-coupled serial bus between the Master and Slaves are an adaptation of Bruce's existing one and I'm sure he could explain it better than me as I'm still learning myself. Bruce? ;)
That's it for now folks, I'm sure this post will change quite a bit over the next few days.
There ARE stuff I'm forgetting now offhand and I'll put it in as I remember them.
dubbleUJay
WJ, The diagram is not correct, it's not a flow diagram, and it's not right as a block diagram. There would only be I2C bus between the serial hub processor and master, and the interface to the up to 8 slaves is opto-isolated current loop, not I2C. I've never seen this before!
Some of the slave functions should be shown, like engine controller and data collection, for example.
OK Bruce, I changed a few thing in the diagram. There's still discrepancies I'm not sure of though.
Surely the actual data being relayed from the Slaves, between the Serial Hub Processor and the Multiplexer hub wouldn't go via the 3to6bit parallel bus that controls the actual multiplexer addresses?
Modified: I've read an email of yours after writing this and will make the changes.
I'll have to draw a diagram for some examples of the Slaves, as I don't have enough place on the existing diagram for it. I left a place holder in the post for it now.
Please let me know if I get the names wrong of stuff, that's a common problem of mine, I once called my wife Mary while she's actually called Xmas! ;) (Only once though, didn't see her for a whole year!)
dubbleUJay
PS- I've sent you so many emails the last few days, I'm sure you missed the 2nd diagram. ;)
Thanks, WJ, much better. The SD card should be moved to the single I2C bus off of the master, there's aren't 2 I2C buses off of a single Arduino.
The serial hub controller is essentially an 8 channel smart UART, with data buffering and an I2C interface to the master. It offloads the overhead of servicing serial I/O from the master. In WJ's system, it's typically about 100 feet between subsystems, (except for one 1000 footer which is going to be a radio link), thus the use of optically isolated current loop for subsystem communications. It's robust and simple.
Jens, you keep gobetwino running continuously and in Kst that I used the 1st time, you set it up to read to the end of the file all the time.
Kst has a lot of setting and I just hit the right combination by accident, I must still read the manual.
I think there must be a way to let Exec update periodically, I haven't tried it this way yet!
Folks,
Just a quick note to let you know I haven't been hit by a beer truck or something... :)
I'm still plugging away on the GUI and the system communications.
I've written a whole bunch of pages on the communications protocol and a quite a bit less on the GUI.
Python should be called Painthon as far as I'm concerned, but I believe I'm getting the hang of it slowly.
I've manages to draw some pretty boxes on the screen with menus and click-able buttons that do what I want.
I decided I needed to define the communications between the PC and the the micro units before I could go on.
So far I've got a command and reply structure that's readable by both human and computer (a big aid to troubleshooting) and that's both flexible and has minimal overhead.
Also, I don't think it will add much overhead to the slave's code.
The only drawbacks I've got so far is that the PC and/or master will need to know what to expect in the replying data stream from the slave.
Also, it's going to be difficult to get the GUI to respond correctly to older data files if the you add to the system later.
(Python is so flexible that it *may* be possible, I'm still learning...)
We'll still be able to export the older data to some other application if we need to via the old CSV method.
It looks like you'll be able to send a command to a given slave by this nomenclature:
CMD#2#4#1Subcommand (two char)
this would send the command "CMD" (a three letter command) to slave processer number 2, which passes the command to slave processor 4 which sends the command to slave 1.
The subcommand is two chars right now, but I can expand if needed later.
I'm thinking of subcommands of AI, AO, DI, DO, ST - or Analog Input, Analog Output, Digial Input, Digital Output and finally Status.
The slaves can be a microprocessor or a 'virtual' slave like a digital or analog or serial expander.
Asking for a full data dump from Master 0, slave 2, digital expander 1 would look like:
DMPS0S2S1 which would then return all of the digital inputs in the form:
DTA021x,x,x,x,x,x, etc. CR
All the slaves strip their address (Sxx) from the command and pass the messages downhill to all their slaves until it hits the right address.
Since all data is assumed to be going to the Master, we don't need a return address, just the address of the sending unit, hence the 021 address after the dta (data) command.
The data will be stored in a file that contains the address of the slave unit (the PC considers the Master to be a slave with the address of 0) in the form of CSV's.
This is still very tentative, so feel free to add you wants/needs/opinions !!!
That Christmas has taken up most of my time lately is my only excuse. :D
Daryl
Sounds like you're making some good progress Daryl. I hope Python will pay off in the end.
Bruce M
That's great news Daryl! I've also been hit by the holiday bug! Not myself, but a secondary condition by the people around me! ;)
I thought this year I'll be ready and I could continue to work through it, but things never turns out that way, maybe next year! ;)
Wow, I've just played mega-catchup with this thread. Seems like it's gone a hell of a long way since I took proper note. Oops.
Have just ordered an Arduino + "experimenter's kit", which has useful stuff like servos, temp sensors & multiplexy latchy things in it :)
As far as what's now being proposed for this DAQ/ECU; unfortunately it's shot far beyond my comfort zone. There's lots of electronic trickery and fancy stuff (I2C) going on which, frankly, I just don't understand...
So, I guess I'll be ploughing my own furrow, but I'll share it with you guys if you're interested.... As a software guy, I'll be sticking with simple stuff when it comes to the hardware. I'll probably end up with a single engine controller, with multiple sensors, which will output data points through the serial port to a PC. The software on the PC will then be tasked with data acquisition/reporting, as well as possibly sending instructions back to the ECU.
Analogue MUXing was mentioned a few pages back: Here's a 4067-based solution that's ready to go, and gives you 48 of the little blighters: http://mayhewlabs.com/arduino-mux-shield. I reckon 48 analogue in/digital in-out pins is plenty... and it wouldn't be hard to hook up another 48 using a second shield (you'd have to use flyleads though).
What about a simple shutdown, like a weight/pulley on the fuel lever, which is held up by a meltable link on the head?
Is the fuel lever un-reliable, and the rack a better shutdown?
The fuel lever just operates the rack.
For emergency shut downs only, sure, a brass wire fuse link can be used. A brass wire fuse link holding the end of the governor spring will also cause a shut down, this I have experimented with myself and found it reliable.
Ade, I'm using a 16 bit I2C port expander for a my battery bank charge controller. It sure was easy to use once I lifted someone else's initialization code. Then all that remains is an I2Cout addr, data command to send a byte to one of the two new output ports. The physical interface is also easy- just two wires with pull up resistors (2K-4K), plus power and ground for the I2C chip. All I2C chips use the same 2 signal wires, only one set of pull up resistors is needed.
I had almost no analog inputs on my Lister(oid) controller, but lots of digital inputs and outputs.
Unless you are doing a bunch of experimental analog data logging, I can't imagine needing analog expansion on an engine controller.
I'd recommend starting with one of the 40 pin Arduino processors, good chance you'd need no expansion at all.
Bruce,
The kit I've bought is this one: http://www.oomlout.co.uk/arduino-starter-kit-ardx-p-183.html It should get here tomorrow, so I can have a little play with it.
Agreed, I shouldn't need loads of analogue pins to make an engine controller; that was in response to some of the posts earlier in this thread where the 4067 was mentioned; thought I'd pass on the link. That said, once I do get into making a "proper" CHP system, I'll want lots & lots of temperature sensors....
Maybe I'll have to take another look at I2C. You certainly make it sound simple - but, then, I've read a lot of your posts which sound simple on the surface, but dig a bit deeper and you're doing really clever stuff...
I can see me needing maybe 2 or 3 temperature inputs for a Lister(oid) controller (1x water & 2x fuel, if I go with heated veg oil), as you say the rest would be digital (rpm, fluid levels). Then lots of digital outputs - idiot lights, throttle, decompression, etc.
I2C is pretty well supported on most processors/languages.
Here's the total initialization code on a Picaxe 40X1:
'initialize for mp23017
hi2csetup i2cmaster,%01000000,i2cfast,i2cbyte
hi2cout $0A, ($00, $00) 'ICON config register for sequential
hi2cout $00, ($00,$00) 'set port direction to all outputs
'After that, it's-
hi2cout $12,(b0) 'b0 or any byte variable containing the 8 bits to be output
hi2cout $13,($FF) ' this is the second 8 bit output port, getting all ones for example
[sheepish]
OK, I just googled. On the Arduino, you need a couple of lines of code:
#include <Wire.h>
(That one references the I2C library)
and:
Wire.begin();
// or Wire.begin(address); to start in slave mode
Mind you, I guess there must be some send/receive code too. Probably also one-liners.
Well, bang goes any excuse I ever had for not using I2C...
(BTW, the page I got that from - http://www.arduino.cc/playground/Learning/I2C - also suggests the processor has its own internal pullup resistors, suggesting that maybe you'd need no external components other than wire?
Ade,
I think the AVR internal pull up resistors might be 10K, you need 2K-4K for reliable operation in my experience. You'll have to check, I'm not that familiar with the AVR processors.
Edit- I just checked and the AVR internal pull ups are 20K- 50K ohms, so for I2C, you must use external pull ups of 2-4K ohms.
Hi guys (Ade)
If you need any info ,just let me know, I'll still post as much as I can, its just that my mind is somewhere else so I'm not going forward or have time with this as much as I'd like too right now.
Ade, ask away, I'm getting notified if someone post on this thread and I will come back to you.
dubbleUJay
Well, I got my Arduino today - a day later than I'd hoped - and all I can say is, wow... Am I ever impressed by this little beastie.
Not only did it work right out of the box, but - with the exception of a bit of string manipulation - it's dead easy to program! And I'm no C programmer either...
So, I started playing around with it at about 2pm, after spending an hour downloaded the programming interface - someone in Italy hasn't heard of broadband... By 2:10 I had it driving a servo; by 2:20 it was reading the temperature (in degrees C) to the PC; 2:30 I had it driving an 8-LED counter; 2.40 saw the merger of the LED counter & temp gauge to make a primitive thermometer. Then the day job got in the way for a while; but, by 8pm, I'd built & written the code for a complete keypad-driven combination lock security system, with doorbell function. This machine makes it SERIOUSLY easy to be productive!
In fact, the only major limitation, it seems to me, is the number of digital in/outs & analogue ins. To some extent, this can be mitigated (multiplexers exist for analogue & digital; although I guess to multiplex a PWM pin would require some clever circuitry), or or one could buy the more expensive ArduinoMEGA, which has more of all pin types. As an indication, my security system needs 8 digital pins for the keypad, 1 for the "ready" LED, one for "error", 1 for "lock active/buzzer"; and a PWM pin to drive the lock servo. Adding a second keypad, for example, wouldn't be possible without some (lots of) extra circuitry & cleverness.
So, happy bunny alert :) I will now design my "killer app" engine control unit, I think ;D
AdeV, I'm so glad you've seen the "light" ;)
Just a thought on the Keypad you described: In the security industry, most keypads are addressable and with the bare-bone Ardiuno's being so cheap, you could have a slave BB Arduino for each keypad and connect them together with an I2C bus to a Master.
Just a thought as I said, more to show the flexibility of the Arduino and a bit inline with what this project is trying to achieve.
dubbleUJay
Quote from: dubbleUJay on January 28, 2010, 07:00:12 PM
AdeV, I'm so glad you've seen the "light" ;)
The "embedded" bulb came on here some years back (before I'd even heard of Lister's slow speed diesels) - but at the time I was planning on scratch-building either a ZX80 or MC68008 based system, which would be programmed in assembler, and would bear more resemblence to a "real" computer than an embedded one...
That idea is on hold, probably permanently - unless I find something which needs raw pace which a compiled C based program can't give me.
Quote
Just a thought on the Keypad you described: In the security industry, most keypads are addressable and with the bare-bone Ardiuno's being so cheap, you could have a slave BB Arduino for each keypad and connect them together with an I2C bus to a Master.
Just a thought as I said, more to show the flexibility of the Arduino and a bit inline with what this project is trying to achieve.
It's certainly an interesting thought. I'm not sure how much external circuitry the Arduino's processor needs to operate, I think you could do away with a lot of what's on the actual board; once you're past the prototyping stage and into dedicated PCBs, I reckon the unit cost will fall even further.
Just a thought, what distance will an I2C bus reliably transmit over? I frequently see it described as "short range"; are we talking inches, feet or yards here? (Bruce, that might be one for you....)
It's a bit early in the morning here Ade and I wasn't thinking that far about the distance, its just a meter or three :(
The opto232 bus described elsewhere in this thread by Bruce would work much further, maybe 30m plus.
The BB Arduino has very few external components and going this way would leave you with a few I/O to use at the keypad as well, that can be controlled from the Master.
Ade, The vendors say 9-12 meters is the max for I2C. I have a hard time believing that for fast devices. I suspect you would have to use the active terminator chips for that.
http://www.esacademy.com/en/library/technical-articles-and-documents/miscellaneous/i2c-bus/general-introduction/i2c-bus-hardware.html
Most chips have hardware asynchronous serial available, so 19.2K baud and higher is often practical. A current loop link, or an optically isolated current loop will do 1000 feet or more, though the data rate will be reduced somewhat at longer distances.
You can also get bare AVR chips with the Arduino bootloader; picking a 40 pin chip would give you the I/O you need without farting around. The little boards are nice for starting and experiments, but I find that when it's time to get serious about getting a job done, you end up needing your own board for interface circuitry and connectors anyway.
While I'm a PIC fan myself (Picaxe particularly), the Sanguino is the Arduino that seems most useful to me. http://sanguino.cc/start I'd just get the bare preloaded with bootloader chip. They do require an external oscillator, which the PIC/Picaxe chips don't.
Here's the basic 40 pin chip with not much else:
http://www.wulfden.org/TheShoppe/freeduino/rbfk.shtml
Just as a little update to this....
I bought myself a couple of Boarduino clones (only £11, half the price of a genuine Duemilawhatsit) - self assembly, but then that's half the fun.
I've also just purchased a K-type thermocouple (good to 1100oC) and a MAX6675 chip. The MAX is expensive, as WJ mentions earlier in this thread; however, it's possible to get them to the UK for about £10 each delivered, less if you can buy in bulk. Not ideal, but they do make interfacing with the Arduino totally child's play.
As for cheaper ways...? Consider:
- You have to amplify the thermocouple signal to get a meaningful value for the A-D converter
- To give a 0-5v range over, say, 0-1100oC, you need to run the amplifier at maybe 9v. So more complex electrically
- As soon as you've got 9v on the board, you need to protect the Arduino from it, not to mention having to supply it in the first place
- You need (ideally) to supply an ice reference. Failing that, you need a known temp reference and another thermocouple junction at the same temperature, to calibrate the "hot" junction
In short.... £10 for a MAX6675 starts to look like quite good value; and even more so if you can get them cheaper than that. Bear in mind also that a high-temperature thermocouple probe is going to set you back a few quid too.... I just paid a shade over £16 for a single 1100oC probe with 1m lead.
So, whats the verdict on the Open Energy Monitor? Is the burden resistor + voltage divider + filter way of connecting CTs & an AC transformer to Arduino inputs safe / durable?
Much appreciated!
David
I have been looking at developing my own automated engine controller using an AVR, AdeV I have not read the entire thread yet but is the thermocouple for exhaust temperature? if you were just looking to measure temperatures up to 150degrees Celcius then a solid state temperature sensor would be your best bet. The LM35 temp sensor outputs a linear voltage range of 10mV per degree so at 150degrees you get 1.5 output which you can amplify if necessary but probably not required before you put it into your arduino.
Ndavid79, I also have been looking at building my own power meter however it just turned out to be too much stuffing around trying to isolate the electronic parts from the mains voltage, it can be done but just with more components than I would like... it can definitely be done other ways rather easily without isolation but I don't want to get ahead of myself with my project, I want to get the basics running like temperature shutdowns and RPM control.
I will start reading through the thread now!
after reading a good chunk of the thread, you were obviously talking about thermocouples for exhaust not normal temps!
I was just browsing some chips and I found something that could help! its a lot cheaper than the MAX6675 as well.
check out the AD597
there is a link do the datasheet here docs-asia.electrocomponents.com/webdocs/0be6/0900766b80be663b.pdf
it's only 6 bucks from rs-components and 10 bucks from element14
They can be programmed to output a direct voltage relating to temperature and work on type J and K thermocouples.
Quote from: carbon-rod on January 04, 2012, 03:58:07 PM
after reading a good chunk of the thread, you were obviously talking about thermocouples for exhaust not normal temps!
I was just browsing some chips and I found something that could help! its a lot cheaper than the MAX6675 as well.
check out the AD597
there is a link do the datasheet here docs-asia.electrocomponents.com/webdocs/0be6/0900766b80be663b.pdf
it's only 6 bucks from rs-components and 10 bucks from element14
They can be programmed to output a direct voltage relating to temperature and work on type J and K thermocouples.
Interesting stuff, thanks for the link. Here in the UK, Farnell do the SOIC package for a fiver, about half the price of the MAX chip. However, there are a couple of issues; it looks like you need quite a fancy power supply to get the full temp range (the data sheet has Vs between -5v and +15v - neither of those is Arduino-friendly. IMHO by the time you've sorted out the power requirements, it'd have been cheaper to buy the MAX chip... of course, that does rather depend on how many thermocouple sensors you're using. I suppose if you end up with a dozen measurement points, the AD597 with it's voltage requirements might end up the cheaper option; but I intend to only have 2 measurement points - right at the head, and just after the heat exchanger - the two temps should give me some idea of how much heat I've captured (have to take losses into account, of course).
Unfortunately, my Lister activities have been somewhat on the back burner of late, due to various reasons. However, it's definitely something I want to get back onto, mainly because it's a lot of fun!
BTW, if you do find an easy way of using the AD597, especially if you find you can reliably use it on a 0v-5v supply, then I for one will be all over it...
hmm ok then damm sorry I didn't look too closely at the datasheet, I will have a look and see what I can find! EGT's should only get up around the 500c range correct?
edit:
ooh lala
I read this in the text
SINGLE AND DUAL SUPPLY CONNECTIONS
In the single supply configuration as used in the setpoint controller of Figure 2, any convenient voltage from +5 V to +36 V
may be used, with self-heating errors being minimized at lower
supply levels. In this configuration, the –VS connection at Pin 5
is tied to ground. Temperatures below zero can be accommodated in the single supply setpoint mode, but not in the single
supply temperature measuring mode (Figure 1 reconnected for
single supply). Temperatures below zero can only be indicated
by a negative output voltage, which is impossible in the single
supply mode
Looks like you only really need the negative supply for lower than 0 temperatures... not a problem for me, plus you don't really need to worry about EGT's below that temp when its running! if you do then you have a problem heh
Quote from: carbon-rod on December 27, 2011, 12:11:35 AM
The LM35 temp sensor
I've used the LM35 a few times now... I'd planned to stick a bunch of them on my hot water tank, to measure the temperature at various levels (I even bought some thermal glue). In the meantime, I made myself a fancy thermometer, 3 LM35s, one outside, one in the "server room" of my cabin, and one in the office side. The external sensor died very rapidly (probably damp), but the server room sensor also died quite early on. I also had problems with the sensors I had on the water inlet & outlet pipes of the Lister when I was trying to determine how much heat I was putting into my water tank - in short, I think the LM35 is a particularly fragile chip... Unfortunately, I've yet to find anything better - not that I've been looking so hard recently.
Quote from: carbon-rod on January 04, 2012, 04:28:32 PM
hmm ok then damm sorry I didn't look too closely at the datasheet, I will have a look and see what I can find! EGT's should only get up around the 500c range correct?
edit:
ooh lala
I read this in the text
SINGLE AND DUAL SUPPLY CONNECTIONS
In the single supply configuration as used in the setpoint controller of Figure 2, any convenient voltage from +5 V to +36 V
may be used, with self-heating errors being minimized at lower
supply levels. In this configuration, the –VS connection at Pin 5
is tied to ground. Temperatures below zero can be accommodated in the single supply setpoint mode, but not in the single
supply temperature measuring mode (Figure 1 reconnected for
single supply). Temperatures below zero can only be indicated
by a negative output voltage, which is impossible in the single
supply mode
Looks like you only really need the negative supply for lower than 0 temperatures... not a problem for me, plus you don't really need to worry about EGT's below that temp when its running! if you do then you have a problem heh
I must admit, I didn't read much of the text (hey, it's late here...), I'll give it a proper look tomorrow(ish). You're obviously right that a negative EGT would indicate some very weird stuff going on. As for max temp, I can't remember what the highest I saw was, but it does increase sharply when the engine is under a heavy load. I may have documented my max temps either here or in another thread, but - as many were at pains to point out - it was hardly a scientific test & errors may abound...
I have only had a quick flick over it as I am at work but it looks promising,
I think I read on another site or here that a diesel engine shouldnt go over 400 or 500 or something... so it sounds like it should work nicely.
It would probably only be used to detect maximum safe loading any way, but you can usually tell that from the amount of smoke coming out of it :)
I found the thread (eventually) here: http://www.microcogen.info/index.php?topic=927.msg11364#msg11364
As most commentators noted, the results are basically junk for various reasons; however, I still find them interesting. I've yet to make the thermocouple holder, maybe this renewed interest will spur me on.
Basically, the highest temperature I saw was 310oC; however, it was probably somewhat hotter by the manifold. I'll repeat the experiment once I've re-done my cooling system, and various other tasks
I just had a read of your post!! man it made me laugh "Due to a combination of wood smoke and diesel fumes, the test was then terminated and the engine shut down." haha I can just imagine, you can only apply so much load before you start a wood fire! you maybe need some Jarrah for longer term loading? hehe
hmm, so did you ever end up making the thermowell for the thermocouple? I'm sure you lost a few degrees in the piping before hand but I doubt it has affected the temperature reading that much, I mean the temperature doesn't need to be absolutely perfect, not for these engines any way.
well it will be a few months before I have built my controller and engine / frame / generator, it's a big project and in amongst it I will also be building a new shed as well.... but I am definitely keen to help develop controller for the engine! I want to get the engine to a completely automated stage with starter and speed control with filters and everything, I mean its completely opposite to how the lister was designed but It's not like it's out in a field in a non maintenance condition.
"The AD596/AD597 can operate from a single supply from 5 V
to 36 V or from split supplies totalling 36 V or less as shown.
Since the output can only swing to within 2 V of the positive
supply, the usable measurement temperature range will be restricted when positive supplies less than 15 V for the AD597
and 10 V for the AD596 are used. If the AD596/AD597 is to be
used to indicate negative Celsius temperatures, then a negative
supply is required."
Looking at the chart, using a J type we can read 500 degrees Celcius with our microcontroller which is 5v output, however we need to supply the sucker with 7V to be able to obtain that 5v output, a small linear regulator should do the trick considering current consumption is tiny, an 8 volt reg from farnell is like 30 cents :) I will have a 12v battery supply and then probably a 7805 5v regulator for power to the microcontroller. There won't be much current draw so I don't see much point in designing a proper power supply circuit, you could use a 5v usb charger from a car but make sure the output is clean because it is a switching supply which can generate noise, I like these though because they are relatively cheap and can efficiently supply 1-1.5 amps producing minimal heat unlike a crappy linear regulator.