I have a G540 unit and cannot get the voltage between the VFD Signal and the VFD Ground to change when I issue a M03 S## command.  I have searched the posts and cannot find the information I need.  Does anyone have a testing procedure for checking the parallel port and the G540 unit?

I have connected the + lead of a variable DC power supply to Pin 9 and the – lead to pin 7 of the G540 unit.  I apply a 10 volt signal and measure the voltage using a digital volt meter between pin 8 and pin 7.  The voltage continuously varies between ~.2 and .45 VDC before I send the M03 command.  Once the M03S15000 command from Mach 3 is sent, I see absolutely no change between pin 7 and 8.  The voltage continues to fluctuate between .2 and .45 volts.   Output 1 does change state and I can control a relay with this signal.

All other features of the G540 work fine; limit switches, outputs, motor drives, e-stop, ect…  I purchased the G540 as part of a “Boxed Kit” solution.  From the other posts I have read, I think this is a newer version as it has the external charge pump switch.

I will be controlling an AC router through a C-19 unit from CNC4PC.  The router speeds are from 10,000 to 21,000rpm.  The C-19 unit is functioning fine as I can apply a varying voltage of 0 and 9.2 VDC between the signal and ground connections on the C-19 and the router speed changes from min to max.

I think I might have a bad G540 unit but would like a testing procedure before I send it in for evaluation.


Thanks
Haze

I have the following settings: