I am using the usb SS board, the CNC4PC C25 board, Mach3. I installed my limit switches in series normally closed so I could use one input on the C25 also if anything happens bad to any one switch the whole mill stops like the e-stop was pushed.

The end of the series is in pin 12 port one and the other is in the grnd port 1. Mach 3 does not see the switch at all open or closed.

Help please

David