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p2-550 remote i/o to the gs4 drive comm error

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  • p2-550 remote i/o to the gs4 drive comm error

    Hi this is my very first project with AD plc and their drives. I have the drives configured and program in the plc and i also have a cmore 15 inch hmi for setting my acc dec and freg and to monitor the current and such out of the drive.
    my problem is that if i cycle the power to the drives the comms locks up another words the in progress on my gs drive write in the program gets stuck on in progress and the only to get it to reset and start working again is to cycle the cpu power,
    Any help would be muchly appreciated
    Thanks Greg


  • #2
    If you are communicating with Modbus and there is a fault in communications, the success bit may never turn on.
    The error bit should come on though and the exception value should show the cause. ie comm timeout.
    If the success bit is used to go to the next item to be read, then it will hang there.
    If the error bit comes on, it can be used to go to the next item or reset the communications at the first item.
    You may have to put some logic along with it as a read/write step may be missed.

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    • #3
      Good morning On my last post i didnt explain the problem quit right. I was told by support at ad that the easiest way to control the drives with productivity is to set them up as remote I/O so this is what i have done.
      so in the software for my P2-550 processor they have made a GSW instruction and a GSR instruction in order to control the drives. Pretty simply "It would seem" , But it has not been.
      My processor has ver 1.2.7.37 firmware My drive has 1.30 firmware and my modtcp card has 1.02 firmware, so all of my devices have the latest firmware in them.
      now first problem that i had was that it said for me to give all my drives an IP so I did but I gave them one of my own as in I went with 192.168.1.50 and so on. But every time i cycle the power to the drive it reverts back to I would guess is the remote I/O port addres as in it goes to 10.20.200.50 so i have left it at those addresses and that seems to work.
      Now the gsw and gsr instructions r setup with automatic polling, and all seems fine for a while until for no apparent reason it stops controlling the drive and all or some of my GSW instructions get stuck on ""IN PROGRESS"" and the only way for me to reset them is to do a hard reset 'power cycle to the cpu'
      This problem is driving me nuts Because it seems as all is good but then for no apparent reason it just stops working. Like if i cycle the power to the drive, the comms lock up and dont reset once the power is back on. Why is this.

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      • #4
        Are you using the communications timeout on the drive?
        If so are you using the reset ladder logic described in the help file P200 to reset the drive section titled "Resetting the GS4 after Error"?

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        • #5
          What is the polling time set in the automatic polling instruction?
          Is it possible that the buffer for the ethernet is filling up if there are to many read/write instructions with automatic polling at a high frequency?
          If you increase the time between polling on the least essential read/write instructions, does it stop faulting or take longer to fault?

          I dont know how the ethernet works on the GS drives as remote IO using the remote IO ethernet port. I have used them, but never had this problem.
          With modbus read/write on the main PLC/Screen ethernet connection, there is an option to skip the instruction if the buffer is more than 75% full.

          This same option is not on the GS Drive read/write instruction.

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          • #6
            HI THANKS FOR THE REPLY I had enabled the comm timeout in one of the drives but it kept activating seemingly without reason and on the plc end my GRW instruction would be stuck on In Progress and would not show a fault and the only way for me to get it to work again another words start and stop the drive would be to cycle the power to my processor. I even left the drive on over night a couple times and when I came in in the morning they were still running Then I would stop and start them a few times and still all good Then I would unplug the ethernet cable and plug back in and that's when it would lock up again. But it doesn't show a fault

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            • #7
              With the drives as remote IO, any failure of the drive may be interpreted as a CPU IO fault.
              Does the program stop when this happens or do other parts of the program function?

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              • #8
                I only have 8 drives and half of them I left on the 100 ms polling and the other half I changed to 500 ms and I haven't looked at the buffer full but I will program in a latch bit looking at the 95% full buffer

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                • #9
                  no everything else in the program works I can even control other drives it just seems to be one or two of the drives at a time that lock up

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                  • #10
                    Is there a value in the Exception Response String in the GS read/write instruction that has the problem?
                    If it is other than timeout, maybe it would point in some direction.

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                    • #11
                      No there is nothing in the string the only thing that happens is the in progress is stuck on with the drives that are working it toggles between complete and success

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