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  • Strange behavior from BRX.

    So, I have built an application, where I'm using MODBUS to talk to 4 GS2 drives, the bulk of it controlling a vertical wrapper.
    The strange behavior is, for instance, if I jog the motor with MODBUS commands, once, twice, it works as intended, starts when I push the button, stops when release. The next time, it may start, but won't stop, like its suddenly missing the stop command, the buttons btw are on a c-more HMI. I use the rising edge of the button push to trigger the run, and invert the falling edge through a PD instruction to trigger the stop.
    The other strange thing happening, I use set/rst on "C" bits to start a cycle of the machine, I have set them to Non retentive in the memory config, the set instructions are triggered with a physical button in one place in the program, it is a toss of the coin at start up on whether these bits turn on by themselves or not....... I have a noise filter on the power line for the PLC, I have unplugged the HMI, I have unplugged the RS485 connection, with the same results, these first few "C" bits may, or may not turn on at startup of the plc.
    I'm using software version 2.6.1, and updated the firmware in the controller yesterday, no change.....

    Anybody??
    anything is possible with the right sized hammer.....


  • #2
    You have a noise issue on the communication(s) line(s) most likely. First update your software and firmware to the latest just to be sure that everything is up to date. If that doesn't fix it, then it is most likely your drives introducing noise. Check your grounding, how you wires are routed, length of the wires, etc. There is a handy troubleshooting guide in the BRX manual in chapter 12 on page 4. https://cdn.automationdirect.com/sta.../brxuserm.html
    If you have an urgent issue, please contact AutomationDirect's Technical Support team.

    AutomationDirect.com Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support

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    • #3
      Originally posted by MrMark View Post
      So, I have built an application, where I'm using MODBUS to talk to 4 GS2 drives, the bulk of it controlling a vertical wrapper.
      The strange behavior is, for instance, if I jog the motor with MODBUS commands, once, twice, it works as intended, starts when I push the button, stops when release. The next time, it may start, but won't stop, like its suddenly missing the stop command, the buttons btw are on a c-more HMI. I use the rising edge of the button push to trigger the run, and invert the falling edge through a PD instruction to trigger the stop.
      The other strange thing happening, I use set/rst on "C" bits to start a cycle of the machine, I have set them to Non retentive in the memory config, the set instructions are triggered with a physical button in one place in the program, it is a toss of the coin at start up on whether these bits turn on by themselves or not....... I have a noise filter on the power line for the PLC, I have unplugged the HMI, I have unplugged the RS485 connection, with the same results, these first few "C" bits may, or may not turn on at startup of the plc.
      I'm using software version 2.6.1, and updated the firmware in the controller yesterday, no change.....

      Anybody??
      So you have non-retentive Cs that are not powering up to the off state?

      Comment



      • #4
        Keeping in mind the lag between the controller and when is shows up on the computer screen, within a few seconds they turn on by themselves, it appears they start out off, but don't stay that way........


        I did go in search of noise problems today, when I cut the power to the two Stellar soft starts I used in this build, the problem seemed to go away, at least the bits turning themselves on.
        The MODBUS comms have still not proven 100% reliable, but, I'm just now getting to debugging my program, now that I seem to have found the biggest gremlin........
        anything is possible with the right sized hammer.....

        Comment



        • #5
          Originally posted by MrMark View Post
          I did go in search of noise problems today, when I cut the power to the two Stellar soft starts I used in this build, the problem seemed to go away, at least the bits turning themselves on.
          Are you using AC or DC inputs into the BRX? And Are the power lines for the starters near the input wiring? Is the starter coil voltage AC or DC?

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