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Thread: OBDII communication help

  1. #1
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    OBDII communication help

    How are you guys communicating with the obdII? I found obdNet which is supposed to be vb and c, but they only have examples in c. Can you guys point me to something that can communicate in vb please WITH some examples?

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    5 days, 149 views, and not 1 response?....in the forum that is supposed to have programmers and developers in it. No help?

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    DriveLine has VB.Net code for connecting to an OBD device, querying PIDs, and decoding the responses. However, it's not a canned DLL.

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    Thanks for responding. I have fixed my issue SOMEWHAT, but not entirely to my liking. So hopefully this dll could resolve my issue, you let me know...if you need to see my code let me know (AutoIt).

    I'm not familiar with the term canned dll, what does that mean? Also is DriveLine free for me to get the dll?

    So my issue with my solution is everything doesn't work exactly as I want. Basically I had to put 60ms sleep between requesting and reading the results. The second issue with this is I cant have all the gauges I want...only two for perfect timing, and three max from quick tests for tolerable fluidity. If I put in more gauges with the sleep, it gets very clunky, not fluid AT ALL, if I reduce the sleep, the queries and samples fly up and all hell breaks loose and it bcomes inoperable.

    Tell me something.

    Thanks.

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    Also depends on your interface...

    If you have a cheap blue tooth unit you may be running into bandwidth issues or issues with your programming language being to slow...

    I don't recall if VB is a compiled language or if it is an interpreted language. ODBII stuff flies by pretty quick but I would suspect it to be an issue with bandwidth of your device if it is indeed a cheap blue tooth dongle...

    If you are connecting to it via a serial port emulator and can change the baud rate you may want to go faster... On a newer GM they send in the neighborhood of 33k baud on the GMLAN bus and 500k baud on the faster CANBUS network... The faster network is likely too slow for anything short of a USB type connection while the GMLAN could be pushing the limits of the hardware... Pre 2006 GM GMLAN bus is only 10k baud so you might be able to pull stuff easier with it...

    So depending on your vehicle your issue might be different.

    Rodney
    Rodney

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    You need to do your OBD querying in one thread and UI updates in another.
    Shouldn't rely on timeouts. Send a query. Wait for response.

    There is no DLL for OBD in DriveLine. It's just sourcecode.

    Hardware should be fine. Some OBD devices run at 9600 baud and can still do 10 queries per second. Good OBD devices can do 40+ queries per second.

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    @ClockWork, as far as the query and ui, that's how I have it set up. I'm not using any timeouts. ...or maybe that's a confusion in the different languages we are programming with? In AutoIt sleep pauses the script for x amount of time, which is what I believe you mean by wait for a response. So I send the request, wait for 10-50ms (dont have it down perfectly yet for smoothness and accuracy and how many gauges), get the response and move on to the next request. If 9600 is good for 10 +/-1 queries per second, then that may be the problem, because it starts looking bad around 14-22 queries per second.

    @redheadedrod I'm using AutoIt, but I doubt thats the problem. I'm seeing the timing on it's functions and it's flying through.


    Currently I'm using the obdsim I found here to get everything working. I thought THAT may be the issue but I dismissed it because the whole system is internal on my computer...How could this slow speed be happening if everything is internal and my cpu and memory load is low?...could the odbsim be it? When I open my port I have the baud set to the standard 9600, could that be all the issue right there? I'll try setting that to a higher baud tomorrow and see what happens.


    As far as adapter, I plan on buying one of these in the next couple of days. I know everyone may go with the LX, but I'm curious about the others, I wish they would all list their bluetooth version and baud rate. I dont necessarily equate cheap (electronics) with no good, unless it's foreign (sorry if that offends anyone). Howevr with what ClockWork said about the queries, I may just default to the LX unless you guys say different.
    http://www.amazon.com/gp/product/B00...=ATVPDKIKX0DER
    http://www.amazon.com/gp/product/B01...A1OOPCOEH374FP
    http://www.amazon.com/gp/product/B00...A1TXJ8YQ6MM9JH

    Thanks.
    Last edited by Champak; 01-20-2016 at 06:17 AM.

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    I just checked if i can change the baud of obdsim and it doesnt make a difference. I set it to 115200 and 256000.

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    If you're using auto-it and OBDsim, I will politely remove myself from this discussion, as I know nothing about either.

  10. #10
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    Thanks I appreciate our help, but what about your thoughts on he obd units I'm looking at? Any thoughts?

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