Hi Ian, Im using a CPU5A4E card but the CPU4 will be much the same when it comes to wiring up the switches.

If you have looked at the CPU4 diagram http://www.edingcnc.com/upload/files...flyer_tech.pdf you will see the home connector, this it easy to wire up. looking at the pin out table in the link you will see pin 1 = X home 2 = A home 3 = Y home 4 = B home 5 = Z home 6 = GND Pin 7 is if you have supplied an external 5v supply to the card (ignore of you have not) 8 = GND 9 = 5v USB (if you are powering the card from the USB port.

So if you were wiring the card up in a normal case suituation then you would ideally be using a NC switch, you would run a wire from pin 1 ( x home) to your switch, from the switch back to ither pin 6 or pin 8 (GND) the same goes for the other axis.

Thats about it matey ;)

Simples!