I have a FMD88-10 PLC and am using the Stepper motor output to move a small elevator. I also have three 24VDC Solid State Relays wired to PLC Outputs 2, 3 and 4. These SSRs drive 3 heaters but they are disconnected for now, so it's just SSRs wired to the PLC.
I issue a move command to move the elevator upward. It moves up, stops where it's supposed to, pauses a couple of seconds, then the 3 SSRs turn on. At that point I see and hear a jump or jerk of the Stepper motor. Sometimes a strong jerk, sometimes weak, sometimes not at all. Note, this occurs when the SSRs turn ON, so it is not related to an inductive kick when inductors turn off. The jerk motion is actually moving the stepper motor. Over time, the elevator inches upward away from it's original stopping point. This is unacceptable.
I have not looked at the output of the PLC (Output 5) on the o'scope yet.
I installed a small ferrite bead on the wire from PLC Output 5 and the Stepper Driver, but that didn't seem to have any effect.
I have some UF4001 diodes (as suggested in the FMD88-10 Users Manual) on order, but won't have those until next week.
Looking for solutions or suggestions at this point.
Thanks in advance,
Neal Cooper