Hi,

I'm running my CNC using GRBL on an Arduino Uno.

Sometimes I'm having problem with false alarm from my limit switchs. Usually when powering on/off router and / or dust collector.

I changed my limit switches cables for shielded ones, rerouted limit cables away from the stepper and spindle cables. I also built a circuit with a capacitor to filter the signal.

It helped to mitigate the problem a lot but still, I sometime get false alarm.

Now that I'm building a new CNC, I'd like to get rid of this problem once and for all. Since I'm having drag chain that would be VERY convenient to have the limit switchs cables in the chain along with the spindle and stepper cables.

What would be the best solution to prevent false alarm? 5V,12V, 24V limit with opto coupler?

Thanks