Hi Dustboy,
I recently posted some information on a different thread regarding the ClearPath step input timing error.
One of the important notes is that you should not use a single I/O return path for all of the axes. Each control signal should have its own step/dir path to the motor AND a return path from the controller back to the motor (e.g. 3 axes should have 3 separate return paths to the controller). They can be tied to gether at the controller and put into a single +24VDC terminal but all axes should have complete return wires to the controller. The wires should not be tied together at the motor with a single wire used for the return path for multiple axes.
It is also notable that the ClearPath motors do not require shielded, twisted pair cabling to handle EMI like most other motor systems. How do we know this to be true? Not only did we test the motors for EMI robustness but we also have high volume OEM customers that ship over a thousand plasma cutting machines a year(plasma is the worst case scenario for EMI) and these OEM customers have no noise issues and they do not use shieled or twisted pair cabling. If the customer has noise issues it is related to noise getting to the controller and being sent through the I/O wires. The problems do not arise from the EMI getting onto the cables between the controller and the motors.
That said, we can't prevent EMI from getting onto the controller. If illegal step signals are being sent to the motors, the motors will fault. So the change in cabling may have helped increase noise immunity of the whole system, but it is not required specifically by the motors.
Here is a link to the thread that includes additional information (page 2):
viewtopic.php?f=60&t=5400&p=46583#p46583
Hope this helps.
Tom T.