Our Avid selection in the Controller Cable listing comes with a 14 pin connector to 6 pin connector. The 14 pin connector is attached to the Avid controller box, and the 6 pin connector goes to the left side of our VFD in the PWM port. 

After you have plugged in your control cable, in Avid CNC Mach 4 Configuration under the General tab, select cutting tool: Spindle, and 3HP Avid CNC Spindle and hit save. 

Under the MDI screen you can check that automatic control is working by typing m3s6000. Your spindle should spin up to 6000 RPM, and then M5 to stop.