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controlling servo motor thru serial port

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  • controlling servo motor thru serial port

    Hello all,

    I have a servo controller and I need to be able to control it remotely thru the serial port. I have it working in torque and speed limit now, but don't want to have the external connections. Only serial port and the e-switch. Is there a way to do that? What register do I have to write to to start/stop the motor, if possible?


  • #2
    Found a way to do this by writing to register P3-08 thru MODBUS.


    • #3
      The digital inputs on the servo are important. They make possible to use the drive for compound motions, made of multiple starts and stops.

      the servo enable input allows servo to run. Can be triggered via serial comms like you did, but that means your servomdrive is not configured to use the inputs. This parameter will also stop your run in a controlled fashion. Another way to stop is to cut power to the motor. Some drives have separate control power.

      the digitalminputs representing options for position tell the servo wich stop position to use when running in position mode. There are up to three stop parameters that you can configure, then the corresponding digital input will allow a specific one. The drive needs to be configured in either relative or absolute position- and obviously, to accept digital inputs.
      same with torque and velocity. Not sure how many digital inputs for each, I guess max two.


      • #4
        Originally posted by fpereira View Post
        Found a way to do this by writing to register P3-08 thru MODBUS.
        Yes, you configure this parameter to set which DI's you want as soft inputs and which ones are hard wired. I use two hard wire inputs for safety (external fault and servo enable), the rest I use the MODBUS communication to write to the input status register (which I map to P0-16 for convenience). You can read the output status in the next parameter P0-17. I have not had any issues running 4 servo drives through the same MODBUS using mainly soft I/O for interfacing to Productivity 2000 PAC. This method makes wiring very easy!