X Y & Z axes each have 2 limit switch sockets

First, I declare I am an absolute novice to CNC and respectfully ask you to forgive me for the questions I have below.

My controller board has 2 2-pin sockets for the 3 axes.
I have enabled the hard limit settings but, for example, the Y axis still crashes when homing to the front of the machine.
If I press the 2nd Y-axis limit switch while the axis is moving to home, the machine stops.

Please, can some learned person offer some good advice here?

Thank you.

So, you have two limit switches wired to each socket? Usually, you have two sockets, one for x and one for y. You wire one switch to each of them and place the switches where the laser should home to.
If you have two switches per axis (one on each end), you wire them in parallel. The firmware does not care which one was activated, it’s enough to know that the axis hit one of them.
Maybe you can draw a sketch?

It’s a 3 axes machine, so something is wrong with this whole picture…

@digitalis49 can you supply a photo of your control board, preferably a link to it and it’s documentation?

You need to home all three axes as a general rule, so you should have three connections.


This indicates the Home position switch is:

  1. Defective. You can test this by swapping it with the working switch.
  2. Wired incorrect. This could be a bad cable or the 2 wires go to the N.C. and N.O. contacts, instead of one of them going to the Com contact. Another possibility is that the plug on the motherboard is offset and not on both pins.

Let us know what you discover, and welcome to the Lightburn forum.

My controller, designed by the Chinese had it’s home switches labeled left to right (x, y, z) but electrically z, y, x… Chinese, right to left…

If he’s got a 3 axes grbl controller, it’s likely he needs three switches. Most of these are compiled in to home the Z axes.

The Z axes should home first, then x and y, not necessarily in that order.

Until the hardware is connected correctly, it won’t really work and you can’t really test it.


This indicates he has a full set, 6, switches. The machine appears to be a 3018 type machine with lead screws instead of belts. When you hit a limit, belts slip, lead screws do not.

True. the Z has to clear any parts before any horizontal motion. My 3018 homes X & Y simultaneously after Z was homed.

Beats me… until he comes up with some documentation, it’s all academic.


Copy that! We seem to encounter that issue a lot.

I thank all of you who have read my post and had made the great effort to offer your support - it was all relevant and most helpful.
I think I solved the issue by using Lightburn’s Limit Switch tester.
Activating each limit switch to match the tester’s lights told me my wiring was all over the place.
Matching the limit switch light in the software to each physical limit switch helped me to plug the cables in the corresponding sockets.
What can I say… you have all been so helpful and supportive and I pray I ca, one day, be in a position to reciprocate.
Again, thank you so very much.

What’s that? Where did you find it? I never heard of it :slight_smile: Or is it introduced in 1.7?

Ooooppppssss !!!
Limit switch tester is in UGS.


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