Possible to have home, limit and Z-axis touch off?

Hi all. I've done a fair bit of searching, but so far haven't found an answer.

I have a machine currently setup for 3 axis. I have switches in each side of the X and Y axis to cover home and max limit. Z will only have a home switch installed. I will eventually setup a rotary for A axis, but this won't require home or limit so it frees up the A input on the breakout board.

My breakout board is a Probotix PBX-2 and uses a shared common and a single input for X, Y, Z and A. All of the diagrams show using combined switches in a NC configuration which itself is no problem. But this does raise a problem using a touch off plate for setting tool height on the Z-Axis. If all of the switches were NO, I imagine I could just tap the max limit for Z and use the touch plate to close that circuit and signal the touch off. But if everything is wired for NC I can't see that as an option anymore.

Is there a way to configure a dedicated touch off perhaps using the A axis inputs? Or some other means perhaps? I'm not familiar with probing in general so this may be a completely newbie type question.

Also for the others, I assume I chose maximum limit + home X (or home Y) for the pin configuration in stepconfig?

Thanks!

i think what your saying is " i'm getting short of inputs ! " if your stuck on using a parallel port then install another for additional pins
you can in fact have all your limits and home on one closed loop and the estop on another . that would free up the a axis switch for a touch off plate ,
the reason for a closed loop circuit is that it also give security to faulty wiring , where as an open switch will not

linuxcnc is totaly configurable so you can just about use any pin , but beware their are a few specific pins on a printer port that cant
your correct in using stepconf too , just select the same pin for x y z if you want them all on the same pin

or upgrade to using something along the lines of a mesa 7i43 or 5i25 pci card for more pins than you may ever need .