HMI Pad Forums Main Forums ScadaMobile Support ScadaMobile to Do-more H2-DM1E MODBUS

This topic contains 4 replies, has 2 voices, and was last updated by  John 5 years, 8 months ago. This post has been viewed 2239 times

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  • #20735

    Wesley
    Participant

      I set up the Do-more PLC Ethernet port as 192.168.1.34 and setup a wireless AP so I could communicate with it from my laptop wireless adaptor set at 192.168.1.30. I also used a MODBUS master simulator on the laptop to be sure I could read a holding register. It worked. I tried to read the same register using the sample Modbus-ONE. It tries to connect but comes up with an error. PLC Local IP:192.168.1.34:502 is what it shows for the connection. What should I use for the address to read 40001?
      Thanks,
      Wesley

      #20736

      John
      Keymaster

        On some controllers address 40001 corresponds do Holding Register 1. So in ScadaMobile you must enter HR1. In any case, please can you disclose the error that you get?. Is it a connection error -on the connections tab- or a tag error -on the home tab next to the tag row- ?

        Thanks

        #20737

        Wesley
        Participant

          John,
          When I removed
          remote_host:=”remote.hostname.com”
          it started working and works great!
          The error was “connection refused” but it must have been related to the reomte_host variable.
          Thanks for the quick reply.
          Wesley

          #20738

          Wesley
          Participant

            The next thing I want to try is using an Ethernet to RS-485 adaptor to link a PLC to ScadaMobile. Is there a good low cost converter that you know will work?
            Thanks,
            Wesley

            #20753

            John
            Keymaster

              You should be able to use any Ethernet to serial adapter. Essentially you may find two kinds of converters:

              (1) Modbus/TCP to Modbus/RTU converters
              (2) simple Ethernet to Serial converter

              The (1) perform an explicit conversion between modbus flavors. When using them you must set Modbus/TCP on the ScadaMobile app.

              The (2) are cheaper as they simply remove the TCP header and push the rest through the serial line. They do not understand modbus. In this case you must set rtu_mode=1 on ScadaMobile. This tells the app to embed Modbus/RTU frames on TCP instead of producing actual Modbus/TCP frames. In this case the converter will simply output what is on the wire, which will be already Modbus/RTU on the serial side.

              Both kind of converters will work, but (1) tends to be more reliable on the ethernet side because retries due to serial line failure or collisions will be handled by the converter firmware on the serial side.

              Thanks

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