Re: VFD interface to other equipment.
Either you are not getting the control from signal from Mach or the output of the G540 may be shot.
You should get ~1v or so from 48v GND (common) to the relay pin connected to the G540, and 48v from GND (common) to the other pin, if 48v on both, then the relay is not picked up.
Do you have a diode to place across the coil?
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.