Thank you for the reply
My Ajax board connects with an ethernet cable, not thru the parallel port. The Ajax board has a plug on the board marked "probe", its connections are at pin 10, +12volt, and Pin 5, -12volt. I ran another software program (CNC11) and the LEDs on its diagnostic screen showed I was connected to the right pins. When I restart Mach 3, the LEDs won't light. I can't check the continuity of the wiring because it uses fiber optics. I'm not sure how to contine.