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Modbus Issue

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  • Modbus Issue

    Forewarning - Im not a programmer

    DL06 with Ziplink - configured for 2-wire Modbus RTU
    Wired to a Babel Buster BB2-7010 Modbus to BACnet Gateway

    Were having a problem where controls contractors are not able to read analog signals. Our programmer says the root cause is the DL06 outputs data in BCD and is not able to change it to a simple decimal value. (4-20mA tank level and pressure transducers mainly) We have no problems with discrete data points. I have never heard of this issue with an analog output and wanted to know if anyone has a simple fix??


  • #2
    He should be able to use the BIN command to convert a BCD reading to binary in the PLC. Do something like:

    LD Vsomething (register where the BCD value is currently)
    OUT Vsomethingelse (unused register)

    You'll need to point your Gateway or Bable Buster at the new Vmem address.


    • #3
      If the "ANLGIN" I-Box is used to set up the module, go there, and at "Input Data Format (0-BCD 1-BIN)", simply change the entry from "K0" to "K1".

      Chances are the DL-06 does not modify the input obtained from the analog input module. In that case, the module setup needs to be changed as described above.


      • #4
        If you go Herman's route, make sure that where ever you are using the analog value in the PLC program, all the instructions interacting with that value need to be changed to the binary versions of the instructions.