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Issue with ModBus communications on 2152 + RS485

J.SmaldoneJ.Smaldone
edited September 2023 in PLCnext Engineer

I am having a timeout error communicating with a modbus sensor. I am using PLCnext Engineer 2023.0.5 Build 6.0.416.0 Rev f248e370. I am trying to use the ModBus_RTU_13 Library on a AXC F 2152 with an AXL SE RS485 to read data from a temperature and humidity sensor. I have checked my serial parameters are matching, but I'm not sure if there is something else I am missing?

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Comments

  • J.SmaldoneJ.Smaldone
    edited October 2023

    I am still having this issue, I am attempting to send and receive data from a valve, and I have created a buffer to track the changes of the diagCodes for the function block I am using. I can see the TX light flash only once a cycle Can I get some feedback as to how to resolve this issue?

    The last four diagCodes I recorded are: 16#8300 0000 , 16#8000 0000 , 16#C110 0001 , 16#8300 0000

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  • J.SmaldoneJ.Smaldone
    edited October 2023

    I have figured out the issue here;

    • addressing should be 2 instead of 40002 etc,
    • FC23 not working, swapped it out for FC6 and FC3
    • double check 485 wiring polarity

    I'm able to monitor and control Modbus devices now

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