ControlWin Modbus slave exceptions

Runtime
mstelt
2017-09-14
2017-10-02
  • mstelt

    mstelt - 2017-09-14

    I have a PC running control win as a slave and a SCADA program which is the master.

    When I run both the Control win and the SCADA program on the same PC I get exceptions on my modbus messages. When I install one PC with control win and another one with the SCADA program everything works fine. I'm trying to read and write.

    This is the log that I captured with Wireshark when both are running on the same PC:

    1 0.000000 192.168.1.150 192.168.1.150 Modbus/TCP 52 Query: Trans: 16482; Unit: 1, Func: 4: Read Input Registers
    3 0.004993 192.168.1.150 192.168.1.150 Modbus/TCP 55 Query: Trans: 32866; Unit: 1, Func: 16: Write Multiple Registers
    5 0.004993 192.168.1.150 192.168.1.150 Modbus/TCP 49 Response: Trans: 16482; Unit: 1, Func: 4: Read Input Registers. Exception returned
    7 1.000250 192.168.1.150 192.168.1.150 Modbus/TCP 52 Query: Trans: 16483; Unit: 1, Func: 4: Read Input Registers
    9 1.000250 192.168.1.150 192.168.1.150 Modbus/TCP 55 Query: Trans: 32867; Unit: 1, Func: 16: Write Multiple Registers
    11 1.001251 192.168.1.150 192.168.1.150 Modbus/TCP 49 Response: Trans: 16483; Unit: 1, Func: 4: Read Input Registers. Exception returned

    This is the log when running on different PC's

    1 0.000000 192.168.1.200 192.168.1.201 Modbus/TCP 66 Query: Trans: 16426; Unit: 1, Func: 4: Read Input Registers
    2 0.000280 192.168.1.201 192.168.1.200 Modbus/TCP 65 Response: Trans: 16426; Unit: 1, Func: 4: Read Input Registers
    3 0.000988 192.168.1.200 192.168.1.201 Modbus/TCP 69 Query: Trans: 32810; Unit: 1, Func: 16: Write Multiple Registers
    4 0.001244 192.168.1.201 192.168.1.200 Modbus/TCP 66 Response: Trans: 32810; Unit: 1, Func: 16: Write Multiple Registers
    8 1.503473 192.168.1.200 192.168.1.201 Modbus/TCP 66 Query: Trans: 16427; Unit: 1, Func: 4: Read Input Registers
    9 1.504294 192.168.1.201 192.168.1.200 Modbus/TCP 65 Response: Trans: 16427; Unit: 1, Func: 4: Read Input Registers

    What could be wrong?

     
  • eschwellinger

    eschwellinger - 2017-09-21

    Hi,
    either you need to add the exception code or add a wireshark capture.

    BR
    Edwin

     
  • mstelt

    mstelt - 2017-10-02

    Hi,

    I don't get a exception code. The pasted lines above are copied fro the Wireshark log file.

     

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