Limit Switches Are Not Talking To My Shield

The limit switches are wired properly and when it needs to stop the switches do not stop and now has broken all of my stops please send three more.

Are they turned on? Open UGS and type $$.

$21 should be = 1.

Try emailing directly and I’m sure they can help you address your problem.

This page shows all the settings:

Also, unless you have explecitly set them up in GRBL as limit switches, then you should not think of them as being able to stop anything. Only to be used to set the home position.

Until you manually go in and set soft limits or change the setting for the switches, they are only Homing switches.

This being the case, if you manually jog the machine past where they are set up, then it will break them.

I’ve looked for previous threads about this from CrisA and didn’t see anything, I think maybe we jumped into the deep end too soon with UGS and checking for settings? When you broke the switches, were you trying to home your machine in Easel (or going through the Easel setup), or were you jogging your machine around?

As @sketch42 mentioned, by default they’re just used to home the device, and not to actually stop the device if you try to move it past a limit. I apologize if you’re an advanced user and using UGS, in which case you’ll want to follow Erik’s advice for checking/changing your advanced settings.

1 Like

I was using easel, my wiring is superb so it is not the wiring. When I flashed it the to correct grbl settings I may have made the assumption that it sets the limits because when I homed it; the switches worked; then when I ran a basic program to mill a circle it was extremly fast and wrecked into the frames as if the switches were not talking at all? Is there something else that can cause this Ive just finished reading configuring v0.9 and I did everything correct.

When I open UGS I get alarm error codes and I cannot stop them long enough to check settings, how do I get around this?


Well, the good news is that you had everything working per spec. The bad news is that you need to think of them as homing switches, and not limit switches. When you say you “flashed it to the correct grbl settings”, I assume you mean that you loaded the standard X-Carve grbl image.

If you want the switches to behave like standard limit switches, you’ll most likely need to run shielded cables to them, otherwise the electrical noise from the spindle will cause too many false triggers. Then you’ll need to change a setting in grbl to enable the behavior. I believe a couple of users on the forum have gone this route, you might be able to find some other threads on the topic.

1 Like

If Homing works correctly on your machine then your hardware is working correctly.

Here are the Homing settings"

$22=1 (homing cycle, bool) — enable Homing
$23=0 (homing dir invert mask:00000000) --------- varies depending on your wiring
$24=25.000 (homing feed, mm/min) — default
$25=250.000 (homing seek, mm/min) — default
$26=250 (homing debounce, msec) — default
$27=1.000 (homing pull-off, mm) — default

If you want to stop your machine from going outside the work area then you can do that with soft limits.

The Grbl setting for soft limits are:

$20=1 (soft limits, bool) — enable soft limits

$130=290.000 (x max travel, mm) ---- default value for X-carve 500mm
$131=290.000 (y max travel, mm) ---- default value for X-carve 500mm
$132=100.000 (z max travel, mm) ---- default value for X-carve 500mm

I had to change $132 for my X-carve 500mm to keep the spindle on the Makerslide. You need to test it on your machine but I think I ended up with 88.

Once you have done the Homing cycle you don’t have to worry about interference on the switches because when soft limits are turned on the switches are ignored after Homing and the software will not let the machine go outside the space defined by Machine 0,0,0 and the max travel limits set in Grbl.

This only works correctly if you leave Machine 0,0,0 at the Home position.

Just to be safe I Home my machine prior to each job.

1 Like

You can still use a work offset with this, right?

That’s fine but what he means is you always need to make sure you home your system first so your machine knows where it is or in my opinion the better and accident proof way is hard limits with this filter.


Not so.

If you have hit a limit switch then the accident has already happened. The limit switch just “limits” the damage that might occur.