o<tool_sensor> sub
G21 (use metric units)
G49 (cancel tool offset)
G10 L20 P0 Z0 (clear current offsets)
G91 (switch to incremental mode)

; this section commented out for sim
;G38.2 Z[#<_hal[gscreen.maxprobe]>] F[#<_hal[gscreen.search_vel]>] (probe down)
;G1 Z4.0 (move up 4 mm)
;G4 P0.5 (pause for 0.5 sec.)
;G38.2 Z-6.0 F[#<_hal[gscreen.probe_vel]>] (probe down slower)

; this section used for sim, comment out otherwise
G1 Z-10 F[#<_hal[gscreen.search_vel]>]

G10 L20 P0 Z[#<_hal[gscreen.sensor_height]> - #<_hal[gscreen.block_height]>]
G90 (absolute distance mode)
G53 G0 Z0 (move Z up to 0)
o<tool_sensor> endsub
M2