I just installed limit switches on my X and Y axes, and they are working, but too well. When the carriage hits the switch, it stops, but then when it moves in the opposite direction and releases the switch, it stops again. I have tried wiring to both the NO and NC sides, and the same thing happens regardless. What am I missing?
Possibly “debouncing” — when a physical switch releases, there can be electrical noise that the software sees as additional presses.
Some controller software can be configured to ignore some changes, and sometimes the answer is a small capacitor across the switch that absorbs the transient voltage changes.
That’s at least one possibility…
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Just a thought. If you are GRBL powered check the setting $27. It tells how far to move away from the activated switch and has to be enough to open the switch again. All the switches would have to be adjusted to be open after homing. After it moves this amount…that’s the home position for that axis. It sounds like it’s working OK…
unless you set it for a greater distance.
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I did some research on this control board and couldn’t really find anything on if it is NO or NC. However I did find that hat boards with paired pins are normally NO so I went with that and set up the Y-axis. With both limit switches on the axis in place, I get no reaction to the activation of the limit switch - it behaves as if there is no switch. When I disconnect one end the movement is halted when the switch is activated, but stops again when the switch is released.
This makes no sense to me.
I guess you need to clarify whether we are talking about home switches or limit switches. If you installed limit switches then you need to check the setting for enable or disable which is $21. Look at the chart I attached above as it describes the setting in pretty simple terms. You may want to also describe what we’re talking about here. Grbl, Mach 3, or other. Your original post is lacking certain details that may help people to help you further.
Limit switches. $21 has been changed from 0 to 1. I am using both Easel and Lightburn. Both programs use GRBL.
Just to throw more against the wall, there have been many discussions on if limit switches should be setup NO or NC and it does matter.
When a wire breaks or comes loose from the switch it will open the circuit and if your setup to look for a closed switch on contact it’ll never happen.
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A nitpick; both programs are compatible with GRBL controllers.
- but it is your controller itself that uses GRBL
Some good background reading: Wiring Limit Switches · gnea/grbl Wiki · GitHub (ignore all the ‘advanced’ circuits that people added; the first few paragraphs and the last section are the relevant bits for you)
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