Variation on Z Probe from docs
I have picked up a z probe that is the NPN NO inductive type described, and I wanted to know if it was acceptable to connect the signal (with diode) and ground to the probe header and the +12V coming from one of the always on fans.
It works if I setup type 5 instead of type 4. I just wanted to know if it is an acceptable configuration.
If this diagram is right then I would consider not doing that;
The 12v input is connected to the signal output on trigger, which will send 12v to the probe signal pin which is designed for 3.3v input. Not Good. If this were a 5v system like ramps/mega, I would say try running the probe on 5v some will work okay and therefore its not an issue, but it will definitely not work with 3.3v as the power supply to the probe.
Your options are a voltage divider (two resistors- google it there are calculators to help chose which resistors) or a 3.3v volt regulator between the signal and the Duetwifi or a relay which is quite a nice idea, you switch it with 12v from your probe but then use it to switch 3.3v to the probe pin. Its nice because you can change from NO to NC (better fail safe operation, as a broken probe shows as triggered).
I think the diagram in the previous post is how they are suggesting you connect the probe to other equipment, not what is inside it.
I suggest you connect the brown and blue wires to the always-on fan connector, and the black wire through a small signal Schottky diode to the endstop STP pin, cathode to the black wire.