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J1850 crc

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  • J1850 crc

    I'm trying to create an equation to enter in to an excel spreadsheet to calculate the CRC. I'm doing something fundamentally wrong as I never get the right result.

    For J1850 the divisor is 0x1D

    So if I was calculating the CRC for 61,6a,F1,01,00

    wouldn't the answer be =~(616af10100-INT(616af10100/1D)*1D)
    This finds the remainder of 616af10100/1D and then takes the ones compliment.
    The answer should be 0x0A, the above gives 0xF9

  • #2
    split63,

    That's because the formula you're using is wrong. The algorithm to calculate CRC is a bit more complicated than that.

    There is code out there, than can calculate the CRC for you, for instance:

    http://obddiagnostics.com/obdinfo/CRC.txt

    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.

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