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Thread: Key bytes and electrical level in ISO14230-4 protocol

  1. #1
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    Key bytes and electrical level in ISO14230-4 protocol

    Hi everybody!!
    I am implementing an ECU for KWP 5 baud init.
    I've read that the initialization is equal to the ISO9141-2, varying only the key bytes.
    The tester sends the 0x33, my ECU responds with 0x55 and then I tested with the E9 8F key bytes, but the tester does not reply with the inverse of the second byte key as it works in theory.

    Is there also some minimum in the electrical level to run the KWP 5 baud init?

    Thanks!!!

  2. #2
    Low Bitrate remus08's Avatar
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    Hi,

    Electrical level are 0 - 12V and only the diagnostic tester have a 510 Ohm pull up.

    For the key bytes, I do not remerber well and it works, but I confirm the ISO14230 key bytes are the same as ISO9141

    I don't know if I could help but at least I've tried

    ---------- Post added at 12:24 AM ---------- Previous post was at 12:16 AM ----------

    I'm back, I've checked on the ISO14230-2, there is timing to respect between each step of the initalization...
    No other clue from my side

  3. #3
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    Thanks remus08 but sorry I was confused with the key bytes, they are 8F E9 instead of E9 8F.
    I think key bytes must be differents for ISO9141 and KWP 5 baud init because then, how do they differ?

  4. #4
    VENDOR - ScanTool Vitaliy's Avatar
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    KeyByte 1 is $E9, and KeyByte 2 is $8F, so you had it right the first time. Are you sure you are following the timings in section 5.2.4.2.1 of the ISO 14230-2 standard?

    By the way, I hope you are doing this for fun, because a cheap KWP simulator already exists.
    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.

  5. #5
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    Thanks Vitaliy! I am trying with these key bytes that you say me.
    Yes, the times of ISO14230-2 I think I respect them.
    I am building an ECU simulator for a career project

  6. #6
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    Guys I have a problem with a car which is EOBD and what it does is that it connects correctly to my app the very first time I plug in the interface but from the second attempt and on it won't connect! I thought I just needed to use the ATZ command each time to initalize the device and then it would connect but if this has been done once then nothing happens..

    Why is that? What is different at the first time you plug the interface and run it?

    Thanks

  7. #7
    VENDOR - ScanTool Vitaliy's Avatar
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    @Nitroking: are you waiting long enough for the ECU to time out (~5 seconds)? Which interface are you using?
    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. #8
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    What do you mean by timeout? I mean what is this process?

    I'm using two chinese clones at the moment, one is really good, the other one is really crap.. Actually it stalls in the 0100, 0120 and 0140 commands..

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