Is there a way to prevent Mach 2/3 from sending a PWM signal to the spindle?  I am using a relay that will die if it is being constantly switched on and off by a PWM signal.  I only want the relay to turn on or off, thus a simple high or low should come from the step pin.  The motor has its own speed control. 

Thanks,
Nishant

Uh, yes just don't configure the spindle as PWM control Then set up the correct output to use for M3 (spindle on) for the relay. I would suggest taking a look at the Mach manual to get a good overview of how to configure things.