OBDII / Elm MPG meter. Almost working but not quite! - Page 5

god_of_cpu · 09-20-2004, 02:00 PM

I'm currenly adding some "extra" PIDs and conversion functions I found. I'm not quite sure what they are if they are just more standard or extended, if they only work with specific vehicle etc., but I found them here: http://www.ghg.net/dharrison/OBDScanAPI.PDF in mode 1 PID 0x21 and up. I'm assuming there more OBD II standard codes possibly a newer revision?

I'll be testing them out later today. Let me know if you know anything about these PIDs.

darkhalo · 09-20-2004, 02:04 PM

forgive me for my ignorance but has anything changed regarding the 2.5 updates per second?

Thanks,
eric

god_of_cpu · 09-20-2004, 02:28 PM

Yes actually, while debugging on the weekend I discovered that the SetTimeout function was actually never working. It turns out ELM made a second version of the chip and only this second version has the function enabled, which they just plain don't mention in thier documentation. I have the first version, but I just ordered the second version this weekend so I can test with it. Using the settimeout function it should be possible to change the amount of time the ELM waits before sending another command. This should make it possible to get updates closer to 10 times a second depending on your car's OBD II hardware. The timeout will be controlled by the configuration dialog in the plugin.

I also discovered that if your car uses the PWM protocol, it should be possible to get updates as good as 40 hz, however, not with the ELM, which tops out at 10 hz. Check out http://www.obd-2.com/ for more info.

stevieg · 09-20-2004, 02:44 PM

OK, I'm up and working using the latest version of the API, and updated all the functions successfully, and the Faker DLL works perfectly.

Still not working in the car so far though!!!

The code that I'm using is here http://www.stevegoodman.plus.com/ECUData.zip , left with all logs after running it (nothing seemed to show up though) - the two batch files are to copy the ELM/Faker to a single DLL so I can switch between them.

Attached is the error message - I couldn't see anything in the log

god_of_cpu · 09-20-2004, 03:15 PM

That error is because it's sending a command to the ELM that is not understood by it. Which means it's communicating with the ELM and recieving data back, but the data it recieved back is a question mark ? which usually means an undefined command was sent to the ELM. I'm going to add another debug statement to that function to output exactly what is sent and recieved when that error occurs. I'll run your code in an hour or two when I get home. Did you try ignoring the error?

Which version of the ELM are you using BTW?

stevieg · 09-20-2004, 03:26 PM

Quote: Originally Posted by god_of_cpu

That error is because it's sending a command to the ELM that is not understood by it. Which means it's communicating with the ELM and recieving data back, but the data it recieved back is a question mark ? which usually means an undefined command was sent to the ELM. I'm going to add another debug statement to that function to output exactly what is sent and recieved when that error occurs. I'll run your code in an hour or two when I get home. Did you try ignoring the error?

Which version of the ELM are you using BTW?

I think I tried RETRYing. I'll go out to the car and try IGNOREing.

It's the ELM 320

god_of_cpu · 09-20-2004, 03:39 PM

You should've also gotten stuff in the log when you saw the assert telling you which command cased it, it probably just didn't write the file when you clicked retry. I'll update the log write so it flushes the file every time hopefully that will help.

The 320 looks exactly the same as the 323 so thats probably not the problem... Do you know if its the v1.1 of the 320 or the v2.0 of the 320? It outputs this when you issue an ATZ command to it. I will try and add this to the next update so it logs the version when it connects...

stevieg · 09-20-2004, 03:47 PM

Right I've just tried again in the car and pressed ignore.

I've drove up and down the road and here's the log. I stopped and started it after driving, I don't know if that's in the log too.

So now I actually have something working, I have noticed it didn't seem to get the correct data. It said 40MPH, -119 Fuel trim, 4163RPM, and something else for the MAF - can't remember it all. Weird thing was it didn't change - just output the same data !

Below is the log file.

Code:

====================================
Log Started: Sep 20, 2004 - 21:30
====================================
CELM323 : COM port 1 opened successfully
CELM323 : Resuming data polling...
CELM323 : Resuming data polling...
CELM323 : Resuming data polling...
CELM323 : Resuming data polling...
CELM323 : ELM device reset!
CELM323 : Echo Off
CELM323 : Killed threads!
CELM323 : SERIAL ERROR!
CELM323 : Failed to set timeout!
CELM323 : Killed threads!
CELM323 : COM port 1 opened successfully
CELM323 : Resuming data polling...
CELM323 : Resuming data polling...
CELM323 : Resuming data polling...
CELM323 : Resuming data polling...
CELM323 : ELM device reset!
CELM323 : Echo Off
CELM323 : Killed threads!
CELM323 : SERIAL ERROR!
CELM323 : Failed to set timeout!
CELM323 : Killed threads!

By the way I think it's the V2 - it's about a month old.

god_of_cpu · 09-20-2004, 04:30 PM

Yes, it seems to be working as it should be, the reason why you are getting the assertiona failures is cause SetTimeout is failing. I get those too, although it shouldn't be since you should have version 2.0 of the ELM interface. All the data will be wrong cause of the error I mentioned earlier with the conversion function. I'm compiling now and as soon as I get all the bugs fixed I'll upload a new version that should give you the correct values.

god_of_cpu · 09-20-2004, 04:37 PM

Heres just the updated DLL... Untested, I'm going out to my car now, but it should work better then your current one. I no longer try to set the timeout in this one.

stevieg · 09-20-2004, 04:37 PM

Quote: Originally Posted by god_of_cpu

Yes, it seems to be working as it should be, the reason why you are getting the assertiona failures is cause SetTimeout is failing. I get those too, although it shouldn't be since you should have version 2.0 of the ELM interface. All the data will be wrong cause of the error I mentioned earlier with the conversion function. I'm compiling now and as soon as I get all the bugs fixed I'll upload a new version that should give you the correct values.

I'll check the interface version in the morning - getting late here and it's a pain to hyperterminal to it using the OSK and touchscreen

I'm chuffed to have something working though and can't wait to try the new version in the morning! Now to start working on some graphics for some gauges

god_of_cpu · 09-20-2004, 09:54 PM

I tested out the dll and fixed a few more bugs. I also havent been able to get any of the new PIDs above 20 to work. Let me know if you have any success reading them.

The only 2 current bugs that I know of are the timeout in the configuration dialog does not update the timeout label and the packet generating function still generates incorrect packets which should just effect the faker plugin which I havent updated either.

I still want to add support for Mode 9 PID to get the vehicles VIN and the mode 5-7 pids for running tests, but I can't seem to find any documentation on these have any links or any clue on how these work?

Curiosity · 09-20-2004, 11:32 PM

Above 20 hex? From what I remember, PID 0 of most modes gives you a 32 bit value of what PIDs are available up to 1Fh and if bit 0 is set, then PID 20h is available which is another set of 32 bits, and so on with 40h, 60h, up to 100h. I don't know what they are past 20h though.

Mode6 is probably the only other interesting one. Each PID has 5 bytes which are 8 bit flags, 16 bit value, 16 bit limit, and can return more than one response to one request.

stevieg · 09-21-2004, 06:07 AM

OK, I'm still not working completely yet....

No data coming in like it should be.

I've got a log from your DLL.

When I went into Hyperterm for some reason it polled a massive buffer from the ELM that must have been requested by your app... I've attached that too..

god_of_cpu · 09-21-2004, 08:40 AM

Are you running with the DLL attached to this page or did you redownload the SDK from the site. The DLL attached is no longer up to date. Download the SDK for the latest updates.

I can tell the log file you sent me is coming from something thats not the latest compiled DLL. Its possible that the latest DLL didn't get into the zip file I uploaded though.