Joint 1 on limit switch error while loosing step

I got a weird error on my machine:

the machine:
50" x 50" R&P drive gantry style router

driver: G540

PC: intel Atom

I'm cutting air with about 200ipm and every now and then, I hear a clunk (the pinion jumped out of rack, I think it's loosing step) and Linuxcnc show Joint 1 on limit switch error

- I have limit/homing setup for all axis, and none was triggered.
- the latency test of my machine is about 24000, I set it from 20000 to 80000 and this issue still occurs
- the limit switches are set to be NC and the two limit switches are serialized (the lower limit also act as homing)
- I can rapid the machine at about 1000ipm and it seems to move fine
- I try to lower the max speed of the machine down from 1000ipm to about 300ipm, this issue still occurs

There's two weirdness here:
1. why does it loose steps? even at 80000 latency and 300ipm
2. why does it say joint limit switch error when loosing step?

my theory is that when loose step, it cause the machine to shake a bit, that caused a electric noise and the wire for the limit switches are not shield, so that caused the limit switch to act weird? but with a NC switch it should be pretty resistant to electric noise right?

Its hard to tell which happened first since a "joint on limit" error will stop all motion

My guess would be that "Joint 1 on limit switch error" probably indicates either a failing limit/home switch or wiring
or electrical noise. With LinuxCNC running, I would check all the switch connections and tap the switches to see
if they have a mechanical issue.

If you don't find a wiring/switch issue,I would try adding debouncing to the limit switch signals in hal

I tried trigger the limit switch when the machine is moving full speed, but didn't hear the "clunk" sound, so I think the loosing of step happened first.

and I did tap on all switches, but connection seems solid

I'll try debuncing limit switch (whatever that is)

so on the machine latency side, what can I try to solve the lose step issue? lower the speed of the machine even more?
80000 is already a pretty high latency, can I increase it to say 120000 just to see if that solves the problem? I know at that latency the machine probably won't run nicely.

thanks for the help

I think is most likely that you are _not_ losing steps but rather
getting false triggers on the limit switch (which will cause an abrupt stop)

Thanks, I'm not sure the limit switch trigger will cause a abrupt stop. AFAIK the limit switch will cause linuxcnc to stop charge pump, and that will cause G540 to cut power to all steppers, right? so it should "glide" to a stop. but given my machine is new build, and haven't break in fully, everything is pretty tight, when I manually trigger the limit switch, it just stopped moving, no clunking sound.

A joint on limit switch error _does_ cause Linuxcnc to stop
So you problem is more likely a limit switch issue than a step loss issue