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J1939 Decoding bytes

  • phn91

    phn91 - 2021-01-10


    I'm new here to this forum, but i am working for a long time with IFM PLC's and codesys 2.3
    but now i have a machine i like to read out and control via J1939, it has J1939 protocol but with custom bytes. see attachment.If i use the J1939 SPECIFIC REQUEST it delivers a DWORD what will not do the job. Any one any ideas how i can read these messages with codesys 2.3? Any idea's are very welcome.


    Last edit: phn91 2021-01-10
  • mersonggs

    mersonggs - 2021-06-04

    Hello, I believe you may not be decoding the PGN bytes properly, I'll leave two documents for you to understand how to proceed to get the correct values.

  • mersonggs

    mersonggs - 2021-06-04

    I forgot to attach in the previous answer, but with this executable program attached, you can put the ID of the messages that are in your document by taking the initials "0x18" which will generate the PGN number that you can consult in the documents I attached in the first answer, it instructs how to use the byte values to extract the values of the variables.
    I'm also attaching an example image getting the number of the first message that is in your CAN attachment, I used the message 0x18FF01D1 inserting in the program only the part "FF01D1" in the CAN Identifier field, below you can also see that it generated the PGN "F001 " in Hex or "65281 in decimal, the Priority and Address are also informed, the PDU format and the Specific PDU are also informed.!


    Last edit: mersonggs 2021-06-04

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