T100MD2424+ & DC Motor Noise

[mike_odc]

I am using a T100MD2424+ interfaced to two stepper controllers and I am also using one of the high current outputs to interface to a 24VDC brush motor.  I am having a problem with the 24VDC brush motor inducing noise on the Tri-PLC stepper pulse train outputs and causiing the stepper motors to move (very slow) and not hold position.  My application turns on the 24VDC motor when the application starts and will turn off the motor at the end of the cycle.  I am not using the PWM functions with the 24VDC motor and the Tri-PLC output wires and motor wires are ran seperately from each other.  When the 24VDC brush motor is not running, the stepper controllers hold position.  Any suggestions?

[support]

Did you add any snubbing capacitor across the power terminal of the brush motor to absorb the spark that could occur during the rotation? This not only could resolve the problem but will protect the brush contact in the motor.

If the PLC is not sending out pulses to the stepper controller but yet the stepper motor starts turning when the motor turns, then the noise is actually picked up by the stepper driver and  not by the PLC. Most likely the noise is either picked  up by the connecting wire between the PLC and the stepper driver or from the power supply. Is the 24V power supplied shared by the PLC, the motor and the stepper driver?

Does your stepper controller have an optocouple to isolate the signal? If the stepper driver uses TTL signal for its control signal then it is more suspectible to noise pick up than optocouple type.

[mike_odc]

I will try the snubbing capacitor across the power terminals of the motor.  

I am sharing a regulated high quality industrial  DC power supply between the stepper and controller.  The stepper controller is the TTL type.  What's interesting is this problem has only occured on 1 of 5 machines.  All machines are wired the same (ie. wire harness).   I will keep you posted.