Limit Switch Lockout: GRBL freezes

From the original Synthetos forum (2011–2025)

Started by philmurp on in grblShield Support. 1 reply, last activity Nov 28, 2013.

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So I have wired limit switches into my X and Y axis. When I wire my limit switch, and then enable hard limits with $16=1, I cannot move my steppers. No matter what command I input, it will not execute. It seems like my limit switches are freezing my system. My G-Code Sender doesn't give any alarm or any indication that the limit switch has been triggered. When I try and make a move to say G0 X-2, my X-Axis light flashes for a second then the system doesn't recognize any commands beyond that point. When I try a soft reset of GRBL at this time, it says 'wait interrupted by user'. I have tried using just one X-Axis limit switch and all sorts of combinations but I cannot figure out what is causing this issue or even what the issue is. When I close out of my grbl controller and restart the system and input $16=0 then everything works fine so it does appear to be an issue with my limit switches. I am using grbl .8c and wiring my limit switches between pin and ground in NO orientation with a 10K Ohm Resistor between pin and Vcc.

After reading some documentation, it appears that with hard limits enabled, the grbl is locked until there is a homing cycle run. However, I only have X and Y limit switches and when i enter $H, it homes the Z axis. Is there anyway to set grbl so that only the X and Y axis are homed so that this problem can be resolved?

Thanks in advance for any help or suggestions, I am really stuck on this issue and have not been able to find any documentation online that addresses something like this.

Staff #

Sounds like you are having an issue with the grbl software. This forum is for the grblShield motor controller and HW issues about the grblShield. I'd suggest posting this to the grbl issues list on the grbl github. If I had a ready answer to your question I'd provide one. Perhaps someone else on this forum has an idea.

This topic is from the original forum (November 2013). Your reply starts a new discussion linked to it.

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