I have your Mach3 usb interface board and am interested in the relay board to turn plasma torch on/off. I have a different relay board that doesn't work, it needs 0/5v from output pin to trigger and t

The Mach3 USB interface board requires 24V relays externally. There are no relays on the mach3 usb board. If you use an external relay on the mach3 usb board, the relay connects to the V+ which is 24V and the output pin is the return. Additional Information: I understand what you are saying. Does your relay board work with the Mach3 USB board? If not, what relay board do you suggest to work with this usb controller? Additional Information: Our relay board works with our parallel breakout board. An off the shelf SSR (Solid State Relay) made for 24V should work fine.