Modbus TCP Master->Modbus TCP Slave Variable always 0 issue

Runtime 🇬🇧
danielchang
2018-04-17
2018-04-18

  • danielchang - 2018-04-17

    Hi I am trying to polling MOXA E1242 device by Modbus. The attached file is my project. I am sure the modbus tcp master fieldbus work fine.
    I could see the Modbus polling Ethernet sockets in Wireshark tool that on Raspberry Pi. I have add variables and mapping to Modbus command.
    But I can not see the variable value changed. It's always zero.
    How should I setting to make the modbus polling data mapping to variables? Thanks.

    IMG: IDE.jpg

    Webvisu.zip [233.39 KiB]

     

  • eschwellinger

    eschwellinger - 2018-04-17

    Hi,
    CODESYS does only update variables which are used in the pou's.
    This is a fieldbus independent feature.

    So either use your mapped varibale or change to 'enabled2 - always update'

    BR
    Edwin

    IMG: Enable2.jpg

     

  • danielchang - 2018-04-18

    Hi Edwin,

    Thanks. It's work. But I have more questions.
    1. I can't get two variable value in the same ModbusTCPSlave Channel. see the attached file ModbusTCPMaster_Value.jpg.
    2. Where can I see the memory mapping value like %IW0, %IX0.0 ...
    3. I only could login to Raspberry Pi and start this project once. If I logout and then login again to start project always got "ModbusTCPSlave : Bus Failure" Error.

    CODESYS 3.5 SP12 Patch 2 + CODESYS Control for Raspberry Pi SL 3.5.12.10

    BR
    Daniel

    IMG: ModbusTCPMaster_BusError.jpg

    IMG: ModbusTCPMaster_Value.jpg

     

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