Hey all, I am deep in to finishing up the wiring harness for my

Hey all, I am deep in to finishing up the wiring harness for my CNC and I wanted to just confirm a small detail. I have min/max limit switches on all axis, and I want to also connect my touch plate. Am I correct in thinking that the touch plate should be connected to z-min? It should also be ok to connect it in parallel to the z-min limit switch, right?

The last part would depend on whether you have normally open or closed limit switches.

normally open

I definitely recommend to rewire for NC limit switches configuration.

why is that?

Noise. NC is better.

Interesting. I guess that makes sense. So should i put the touch plate on a-min?

NC limit switches configuration is much less more immune to electrical noise, as the signal pin on the controller board is connected to GND during normal operation and only goes VCC after limit switch gets hit.

Hmm, i guess it uses z-min (but with z-min disabled) and z-max as homing

I have X, Y and Z limit switches wired NC. Additionally Xmax is connected in series to Xmin and Ymax to Ymin and Zmax to Zmin respectively. Xmin (and Xmax) is connected to Xmin on TinyG, Ymin (and Ymax) to Ymin on TinyG and Zmin (and Zmax) to Zmax on TinyG. This way I control both sides limit switches on an axis by one TinyG input. I never reached X/Y/Z max limit switch side.
Xmin/Ymin/Zmax is used for homing.
Zmin is used as NO (normally open) to connect my touch probe to Zmin input on TinyG.

Ok this is exactly what I was looking for! Thanks!!

@sszafran ​ I think you mean NC is less susceptible (or more immune) to electrical noise?

@dhylands ​ You are absolutely right, NC is definitely more immune to electrical noise than NO. At least great to see someone is reading with attention. Thanks.