grblHAL Alarm 12
grblHALAlarmPosition isn't set yet: home first
A limit switch reads as pressed, so the controller won't move until it's clear.
Position isn't set yet: home first. Hamrun's reading: the controller won't trust position with a switch active. (Hamrun's reading)
What to do
- Jog the machine off the switch (homing is usually the only move allowed).
- If nothing is touching it, check the switch wiring and the inverted setting ($5).
What users reported CLAIMED · forum and issue reports, not official
- First-run alarm stops on a Genmitsu 4040: the machine wasn't homed, or was parked against a limit switch. Home first, unlock, then check the job. It was the alarm state, not a dead board. r/hobbycnc thread, Jan 2026 (the thread doesn't name the alarm number)
Official grblHAL message: “Limit switch engaged. Clear before continuing.” source
Got a different message?
Paste it into the decoder. Hamrun's editor checks your G-code before you run it, so a toolpath that leaves the machine's travel or a missing feed rate is caught before the machine stops.
Official text copied from the grblHAL source on 2026-11-01. Steps and the position answer are Hamrun's reading unless marked “firmware says”. User reports are labelled CLAIMED.