ALARM1 when setting 21=0?

[ianmechura]

I am getting an ALARM1 when I start my plasma cutter likely due to interference. I was under the impression that whenever $21=0 the system would ignore signals to the limit switch input pins but I am not observing this to be the case. Did I misunderstand the purpose of the $21 setting? Is there something else that can be done to ignore signal on limit switch input pins?

I'm running GRBLHal on ESP32 30 Pin Dev Kit with a generic, imported, 60 amp plasma cutter.

Thanks

[terjeio]

$21=0 blocks alarm 1 except in one case where it can be raised during homing if "two switches shares one input" is enabled. And it does block alarm 1 for me when testing with my dev board.
Are you using limit switches for homing or are they left floating? And which pins are used for the inputs?
If used for homing can you trigger alarm 1 when $21=0 by activating any of them?

IIRC I had issues earlier with some of the pins beeing triggered by the radio even if interrupts were not enabled - so the issue could be related to interference interacting with the die in a similar way?