Putting the finishing touches on my driver enclosure. The system is based around 3 IM483 drivers, CNC4PC breakout board, charge pump and relay board. Motor power is a 600KVA transformer, rectifier bridge, caps etc delivering 42VDC. Logic power comes from a Power One 5/12V regulated supply.

The 5 and 12V grounds and all cable shields are tied to chasis ground but the motor supply ground is floating about 6V below chasis ground with the system idle. Probably higher with the motors running. What really has me bugged is that the IM483s have a 5V input to power the opto-isolators but no coresponding ground. The only ground is to the motor supply. I m afraid I will fry the boards.

Do I need to tie the motor supply negative to chassis ground?