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1 PLC, multiple HMIs

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  • 1 PLC, multiple HMIs

    How do I operate a single PLC from multiple locations via HMIs? I have the HMIs programed that the work individually with the PLC, now I want to hook multiple HMIs to PLC. I have a C0-02DD1-D and a C0-12DD1E-D. I can use which ever one that is the easiest.

  • #2
    Use the Ethernet Click and connect all the HMIs through ethernet. Old serial Modbus doesnt do multiple master, Modbus TCP (ethernet) will let you do multiple master. The HMI is considered the master and PLC is the slave.

    Or, you can use a serial card on the PLC and connect the HMIs to different serial ports so that really they are single devices, but they all read and write the same memory addresses.

    Ethernet is more expensive but a lot easier to work with in both setup complexity, wiring, and cable lengths.
    Last edited by MikeN; 02-07-2019, 11:04 AM.


    • #3
      i replied in your other thread but what HMI are you using.


      • #4
        EA3-T4CL C-More HMI


        • #5
          i have not used a C-more micro so i do not know if it supports panel pass through. You should be able to use modbus TCP with the ethernet click and connect to both panels but someone more familiar with clicks and C-more micros should be around shortly that would bea able to help better than I


          • #6
            You could retain plc as master and poll the multiple hmi one at a time. This presents the advantage of changing the program parameters from one hmi terminal at a time, rather than concurrent changes from multiple terminals. Then you need to broadcast to all hmi terminals that changes are being made from terminal xxx, to prevent changeovers. That is not to say an operator located at a different terminal can not change again the same parameter as soon as it gains control of the plc.

            Having multiple terminals complicates the scope because will require a user system with different levels of authentication, such as a change made the line supervisor canít be modified by machine operator. But real life tells that the machine will crash because the operator canít do small adjustments dynamically as it should. So is complicated. Will lead to people quarrel over who changed a parameter that crashed the machine.

            multiple terminals are good for monitoring but not for running


            • #7
              Originally posted by Alexandru View Post
              You could retain plc as master and poll the multiple hmi one at a time.
              No, no you can't. C-more does not have a slave capability.

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