CRC Error

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This topic contains 6 replies, has 2 voices, and was last updated by Avatar lgr 11 months, 2 weeks ago.

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  • #3808
    Avatar
    lgr
    Participant

    Hi, erevryone!
    I have a problem,
    SCADACommService make a wrong CRC:
    01 03 30 00 00 08 4B 0C
    I calc the CRC by using some tools,the right CRC shoud be 0C 4B , and i using 0C 4B send the command can get right result. It will get “CRC Error” when i send using 4B 0C.
    How can i solve the problem?
    Thanks!

    #3809
    Avatar
    manjey73
    Participant

    http://modbus.rapidscada.net

    Probably your device is not quite standard. If you use the specified link and check your request, the CRC is correct, the lower byte forward, according to the Modbus Protocol.

    https://www.lammertbies.nl/comm/info/crc-calculation.html

    Online Calc shows just the CRC value as it is.

    I would like to look at this device that does not send CRC Modbus younger byte forward, I have never seen this in the factory products.

    • This reply was modified 11 months, 2 weeks ago by Avatar manjey73.
    #3811
    Avatar
    lgr
    Participant

    Hi,
    Thanks for your reply.
    It is an analog signal acquisition equipment bought through E-commerce website. https://item.taobao.com/item.htm?id=566584520351
    If the problem caused by the device , can i solve the problem by software setting ?

    #3812
    Avatar
    manjey73
    Participant

    Write to the Chinese that they have the wrong byte sequence in the CRC. Well, if it does not help, you can try to build KpModbus.dll in the new version, where you change the sequence of bytes for CRC, and to call it KpErrorModbus.dll 🙂

    #3813
    Avatar
    lgr
    Participant

    Thanks very much!
    I have contacted the vender and confirm the problem.

    #3814
    Avatar
    manjey73
    Participant

    01 03 30 00 00 08 4B 0C

    So it became clear that any online calculator Modbus CRC in the calculation of CRC along with it should give the result 0

    AI 0-20, 4-20 mA

    It was necessary to buy such a module, there is a description in English and you can check the information on the Protocol and the method of calculation of channels.

    • This reply was modified 11 months, 2 weeks ago by Avatar manjey73.
    #3816
    Avatar
    lgr
    Participant

    Yes,
    Thanks very much!

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