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Peerlink for "So called" Hot Backup

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  • Peerlink for "So called" Hot Backup

    Can I configure 2 different CPUs for the same Remote I/O network and use Peerlink (or other) function to operate them as "so called" hot backup system?

  • #2
    How are you connected to your remote I/O?


    • #3
      The connection to the remote I/O will be for sure over over Ethernet


      • #4
        Originally posted by Soal View Post
        The connection to the remote I/O will be for sure over over Ethernet
        What protocol?


        • #5
          I'm actually wanting to now what kind of remote I/O you are talking to. What you are wanting might be possible over Modbus, but difficult or impossible over other connections.


          • #6
            Thanks Bob.
            There is no definition for the protocol to I/O.
            Should be over ETH but protocol type is not defined.

            One of the missing functionalities in all our PLC range is hot backup. Not mentioning real redundant architecture.
            We have currently a request for a large system with many I/O panels that will operate with a main CPU and a backup one.


            • #7
              If you are willing/able to use something like Modbus to talk to your I/O, then yes, it is possible to create a failover mechanism. PEERLINK is easy, but won't be as fast. I would probably use RX/WX between the masters. The challenge will be keeping the backup at the same program execution state as the primary.

              i would recommend that one is always the primary, and one is always backup. Backup is constantly checking for primary to be alive, and immediately yields if it is. That's the way Do-more's time server works, and it was cleaner than having multiple primaries try to decide who is boss.