I got a cheap three axis Chinese CNC3040 wood cnc machine that uses
1. A BL-USBMach Board
2. Three Steper motor Drivers
3. One PWM Driver Board which Drives the 400W Spindle motor.

I have been able to configure the Machine using MACH3 software and I have a good control for the X, Y and Z axis.
THE PROBLEM:
The Spindle Motor is NOT connected to the BL-USBMach Board even though the Board has both a PWM and VFD output. The Spindle motor was configured to be controlled manually from a potential divider knob.

I have tried to modify it by taking the (0-5V) input from the POT to the PWM output of the BL_USBMach Board BUT I dont have any Response. Please if you are familiar with the BL-USBMach BOB let me have your help.
Thanks.

I have gone to to MACH3 software to configure
1. Motor Output as:
Spindle=Enable
Step Pin#=17
Dir Pin#=1
2. Output Signals as:
Output#1+Enabled
Port Number=1
Pin Number=17
3. Spindle Setup
Relay Control=Disabled
Motor Control: Use Spindle Motor Out and PWM Control=Checked