I want to make sure I understand how to wire up proximity sensors. I've read a few threads here about the subject, but want to make sure I'm not missing something. I have a uc100 going to a G540 with a 48volt 12.5 amp power supply running 4 motors. Currently the only input I'm using is a z- touch off plate.



I am considering buying these 10-30volt (or 6-36 or 12-24 depending on where you read the specs) NPN, normally open sensors
1pc TL Q5MC1 DC 3 Wire NPN No 5mm Square Inductive Proximity Sensor Switch | eBay

I would have 5 of these, 2 in parallel with each other for both X and Y, and 1 for Z

I would use something like this for powering them:
Amazon.com: DROK


I would take the black wires and use them as inputs into the g540 on 3 different pins, so that I could tell which axis was being triggered.

My questions:
1. Is it OK to use 12 volts in this configuration, or would I need to put a resistor on the wires going to the G540?
2. In this configuration, would my setting in ports and pins be Active Low?
3. Would I be able to control a spindle with a vfd/ super PID in the future, or am I out of inputs? Could I wire all the proximity sensors to 1 pins and still be able to home the machine?

I really appreciate any help you could offer. Thanks.