Grounding - RPi 4/B - 7i96

RPi 4/B 4 GB with the Debian 2.8.4 RPi4 iso.
A moderately compact installation.

Y-axis and Z-axis jog Ok, but when I attempt a jog on X-axis, no movement.

Swap X/Y drive cables between 7i96 and Leadshine drivers.
Now both axes jog (select X to get Y, and vice versa).

Swap back, X won't jog !!!

Tried several times with same result.

Sounds like a grounding or EMI problem.

Wiring is differential between 7i96 and steppers without any power/ground references.
RPi and 7i96 grounded with mounting studs at all the mount points.
Stepper supply is not grounded.

I have an oscilloscope to start looking ( hope for short learning curve ).

Any specific suggestions ?

 

I would wire the drives single ended and see of that solves the issue

Always check the simple things first !

A check on the wiring found one connection on the driver plug on the backside of the screw clamp.
The screw was tight but the miniature flattened ferrule was loose.

Now jogs all axes.

Thanks for comments,
John.