My setup is a chinese 6090 CNC, Windows 10 PC running Mach 4, ESS, G540,  XYZ axis all working properly.

My issue is with controlling the spindle.   The spindle uses a Delta VFD.   I have it set up to turn on and off via a pin on the ESS, and speed is set by the 0-10V input.
There are Pins on the VFD:  GND, AVI, +10V.   When I connect a potentiometer to these, I can adjust the speed from a low of about 3000 to 24000 RPM - judging from the display on the VFD - I have an optical Tachometer on order...

When I connect the G540 Analog output pins (VFD GND, VFD OUTPUT, VFD +10V) to the pins on the VFD, as I change the requested spindle speed on Mach4, I can only get speeds up to about 12,000 RPM, and the voltage on VFD OUTPUT, seems to max out at about 5V.   I'm pretty sure that this has to be something in the configuration, but I am at a loss as to what it might be - any ideas?

Mark

Is there a supply greater than 5v to the g540?

G540 supply is 18V,  The VFD supply (supplied by the VFD to Pin 9 on the G540 block is 10V)

I think that I have solved the issue - it involved changing the PWM frequency setting in the ESS setup.

Thanks