Thanks Steve, I’ve been worried about this for a long time.
None of the devices/components NEED a common between them. The PC, PoKeys57E control panel I/O and the PoKeys57CNC motion controller communicate through Ethernet so they don’t use a ground or common. All other components like limit switches, VFDs, servo drives and solenoids are either optically coupled, galvanic isolated or relay controlled.
Katz, I use the PoRely8 driven by the PoKeys57CNC controller which is in the machine control cabinet. I use the PoKeys57E in the control console for digital and analog inputs from switches and pots. For control console outputs I use 2 open collector PoExtBusOC16s for the illuminated pushbuttons. The control cabinet and control console are 10 feet apart an this Hurco KM3P mill retrofit with Mach4 and Gecko G320X servo drives. One Ethernet cable communicates between the two.
Some pictures under construction attached: