First thing - does the PMDX-107's self-test mode drive the spindle (see the PMDX-107 User's Manual)? If not, then we need to verify the wiring between the PMDX-107 and your spindle controller.
If the PMDX-107 self-test mode *does* control the spindle, the next thing is to make sure that the PWM signal is getting to the PMDX-126 and therefore the PMDX-107. In general, make sure that the PWM signal is on port 1 pin 16, with a PWM frequency of (typically) 100 Hz. The direction signal should be on port 1 pin 14. With the spindle turned on in Mach and a non-zero spindle speed, look at the LED on the PMDX-126 at connector J6 on the terminal labeled "16". The LED should be glowing, and the brightness should change with spindle speed (dimmer at slower speeds, brighter at higher speeds).
If you see this LED glowing as it should, now check the LEDs on the PMDX-107. The "PWM" LED should behave just like the pin 16 LED on the PMDX-126.
If you are running Mach3, then look at our application note AN002 here:
http://pmdx.com/AppNotesIt is titled "PWM Spindle Speed with Mach3, SmoothStepper, PMDX-125 or PMDX-126 and PMDX-106 or PMDX-107" and it shows all of the settings (SmoothStepper, PMDX-126, PMDX-107 and Mach3).
If you are running Mach4, the ESS plug-in is much different and I do not know how to configure the ESS for this. There are a couple of threads on the MachSupport forums (
http://www.machsupport.com/forum/) , but I suggest going straight to the Warp9 support forums (
http://warp9td.com/index.php/kunena/index).
Bob