PMDX-424 Limit Switches & Proximity Sensors

[bwolfe]

I am building a Joe's 4X4 EVO CNC.  It's been taking over a year since I have a corporate job.  I'm almost done with the mechanical build and hope to start connecting the electronics soon.  I have a PMDX-424 and two PMDX-133's in case I decide to add a lathe later.

Questions:
1) Does the PMDX-424 support gantry squaring now?  I read some posts about that, but I haven't seen anything after 2016.
2) I plan to buy three (3) NPN normally open proximity sensors from CNC Router Parts: one for the left X axis, one for right X axis, one for one end of the gantry (Y-axis).  At the opposite end of each axis, I plan to use limit switches.  On this forum, I read about the merits of using normally closed limit switches.  Since I haven't done anything with Mach 4 yet, I'm not sure what the screen looks like regarding the input terminals.  Bottom line, is it ok to have normally open proximity sensors and normally closed limit switches connected to J16 & J17?
3) I may have misunderstood, but somewhere in the forum I read a note from Bob and he was advising connecting certain limit switches to the same input.  That didn't make sense. Again I may have read it incorrectly.  Each switch should have one of it's wires connected to its own input, correct?

[RonGinger]

Limit switches can be connected together- when a limit is hit the action is to stop all motion- it does not matter which switch is hit, all motion stops.

The safest method is to put all the limits in series. If any switch is hit, or the circuit breaks somewhere it will be seen as a stop.

[bwolfe]

Ron,
Thank you for your reply.  Makes sense now.
Disregard question #2 as I found a cost effective NC proximity sensor.

I still want to know the status of gantry squaring with the PMDX-424 if someone knows.

[webdevl]

I was wondering if you have found a solution to gantry squaring.  I am trying to do that same thing and wondering if I purchased incorrectly for my new machine.