Hi, I'm struggling to make sense of what's happening with my spindle control. MACH4, Microsoft XP, Parallel port and Darwin. I see the pulse rate affects the outcome on my speed? Is that right? My set up is on a 3040 chines mill with the router that comes with the original unit. 300 – 8000 rpm. Putting a taco on it I seem to be getting a range from 5700 to 10830 rpm, and that's trying to control it via Darwin. 0 gives me full speed and 20000 gives me 5700rpm. So from Darwin I get a reasonable range. MACH4 I'm lost. The on/off works, PWM seems to work but not full range and same effect with the min/max freq setting. In the freq range I used 0 to 20000. When controlling from the GUI, there is a limited response from the slider 50 % to 150%, which also has the opposite affect i.e. 50% runs faster that 150%? It put values in at the top when running, 150=50%, 300=100% and 450=150%, but I can't work out where its getting the 300 from? The PWM set up does pretty much the same.