grblHAL Alarm 15

grblHALAlarmPosition isn't set yet: home first

On a machine with two motors on one axis, the second limit switch wasn't found when squaring.

Position isn't set yet: home first. Homing didn't finish. (Hamrun's reading)
What to do
  1. Check the second switch on that axis the same way as the first: press it by hand and watch the pin state.
  2. Check both sides of the gantry move freely and the switch is where the axis can reach it.
Official grblHAL message: “Homing fail. Could not find second limit switch for auto squared axis within search distances. Try increasing max travel, decreasing pull-off distance, or check wiring.” 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.

Related codes

  • GRBL 1.1 Alarm 10: On a machine with two motors on one axis, the second limit switch wasn't found when squaring.
  • grblHAL Alarm 6: Homing was interrupted by a reset before it finished.
  • grblHAL Alarm 7: The safety door was opened during homing.
  • grblHAL Alarm 8: After touching a limit switch, the machine backed off but the switch still read as pressed.
  • grblHAL Alarm 9: During homing an axis travelled as far as it's allowed to and never found its limit switch.
  • grblHAL Alarm 11: The controller is set to require homing before anything else.
  • grblHAL Alarm 18: Homing is set up in a way the controller can't run.

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.