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Thread: Optimizing Scan Rate

  1. #21
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    In ISO there is P3 timer. I am not expert about ISO, but I think it is the minimal delay between last byte from tester and first byte of anwer from ECU. Minimal is around 55ms.
    250ms is long time, but it could be due to ECU.
    Tomas

  2. #22
    Low Bitrate remus08's Avatar
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    Hey,

    To people which try to get sensor as fast they can.
    I've done a test last week on a CAN vehicle. The excel file is available here http://www.woofiles.com/dl-199641-HZ...staST150ch.xls

    I reach 8 readings per second. As soon I've tried with a ISO vehicle, I'll put result.

    PS: the 010C1 command seems to have no effect on the scan rate speed. I have to try to set another timeout value.

    PS2: Obvioulsy I've done that with the software we're developping, see link below

  3. #23
    VENDOR - ScanTool Vitaliy's Avatar
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    Quote Originally Posted by remus08 View Post
    Hey,

    To people which try to get sensor as fast they can.
    I've done a test last week on a CAN vehicle. The excel file is available here http://www.woofiles.com/dl-199641-HZ...staST150ch.xls

    I reach 8 readings per second. As soon I've tried with a ISO vehicle, I'll put result.

    PS: the 010C1 command seems to have no effect on the scan rate speed. I have to try to set another timeout value.

    PS2: Obvioulsy I've done that with the software we're developping, see link below
    What kind of scan tool are you using? What type of connection (USB, Serial, Bluetooth) and baud rate?

    Vitaliy
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

  4. #24
    Low Bitrate remus08's Avatar
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    I used this configuration

    - our software which check received buffer every 10ms (max allowed by windows) and re-send another request as soon as possible. A real timestamp is add to the csv file created.
    - a cheap ELM v1.2 interface using USB protocol with some improvments
    * Baud rate changed to 115200
    * Line feed off
    * Space off
    * Echo off

    I don't knwo how do faster... If there is a way to do faster I'd glad to know it.
    Update baudrate to 200k would make win only 1 ms.

    Another remark, bluetooth interface used to be really slower!

  5. #25
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    I think there is a big gap between question of ELM and answer from ECU.
    You can measure it with simple oscilloscope.
    Tomas

  6. #26
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    Typical delay between command and reply is 30 - 35 mili.
    It is never more than 55 mili, because that means that there are no more replies from other ecu's.
    So, total wait time here for 1 ecu: typical 85 mili.
    For 2 ecu's: typical 120 mili.

  7. #27
    VENDOR - ScanTool Vitaliy's Avatar
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    On ELM327 v1.2 you can play with ATST, progressively setting it to lower and lower values.
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

  8. #28
    Low Bitrate remus08's Avatar
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    Ok, I'm gonna try with lower value for ST parameter..

    Actually, I get 32 PIDs per second, because I ask for 4 PIDs in the same time. The response is a CAN multi-frame response, so a little bit longer than a "single PID request".

    I'm quite sure that the ECM responds really quick. The time should be lost in the ELM chip or FTDI chip. I'd love have a scope to check

  9. #29
    VENDOR - ScanTool Vitaliy's Avatar
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    I'm sure you will have much success with a lower ST value. CAN ECUs are very fast.
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

  10. #30
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    Question ODBSIM, give me more speed?

    Quote Originally Posted by chunkyks View Post
    Oh. I see you're already upping the baudrate - nvm me. [are you sure it's working, by the way? There's a lot more to making the upgrade fully work than just "ATBRDXX"]

    Gary (-;

    ATBRD23 only return ?> to me. How can I get OBDSIM to speed up it's baud rate for testing?

    Thanks,
    Bobby Cannon

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