FX3U for stepper control

[Abra 0]

Hello, I am having trouble getting my stepper motor up an running. I am using an FX3U-16MT/ES PLC.

[Abra 0]

Sorry everyone, somehow my fat fingers sent that post before it was finished. As I was saying I'm using an FX3U-16MT/ES PLC. I have managed to get the stepper motor to move using the sample programs in the positioning control manual. The problem is that the motor only comes on for a short period of time, then stops. It move the same short amount no matter how many pulses you send the the driver. It almost acts as if it is only moving on the rising pulse of the sequence start marker as opposed to starting the movement and completing it with the motion complete command as the program states that it should. Any help on this would be appreciated. Thanks, Jason

[Crossbow 296]

Sounds like the stepper driver isn't reading the pulses properly. I doubt it's the PLC program.

[JRoss 84]

Troubleshooting questions: Which positioning commands are you using? Do registers D8140 (double word) and/or D8142 (double word) reflect the correct number of pulses? Can you verify somehow that the right number of pulses are coming out of the FX3U (oscilloscope, high-speed counter...)? Does the stepper have a max frequency that you are exceeding after ramping up? Is the stepper set up properly to accept and follow a pulse train? Are you giving the stepper the correct voltage (some steppers require 5V) and resistance (for high-speed switching)?