Plasma specific commands

M3 - Start plasma

Request plasma to start and blocks until the arc is transferred or timeout occurs. The timeout value is defined in [plasma] configuration transfer_timeout_ms.

Error cases:

• Ignition timed out

• Arc lost after ignition

• Multiple calls to M3 without M5

Errors automatically stop plasma. In any case, M3 has to be rearmed with M5 before it can be called again.

M5 - Stop plasma

Stop plasma and rearm M3 command.

M6 - Enable THC

args : V<voltage v> T<feedrate threshold mm/min> A<minpos mm> B<maxpos mm>

Enable THC to track a specified voltage by moving the torch up and down.

When XY motion goes under the feedrate threshold, THC slowdown (and eventually stops). When feedrate goes back above the threshold, THC starts moving again.

The torch move between A and B positions if specified, otherwise on the whole z range (but never exceeding rail limits).

Example : M6 V110.5 T2400 A10 B150

See [torch_height_controller] for permanent settings.

M7 - Disable THC

Disable THC. When disabling, only MCU knows the exact position of z axis. M6 can be called again, but no standard z motion can be performed before PC resync its z position.

M8 - Resync z position

Resync PC z position on the MCU.

Example :

M6 V80
; THC is active
M7
; THC has stopped, but only MCU knows where z is
; M6 can be called again, but not G1 Z
M8
; MCU has sent position to PC, everything is back to normal
; G1 Z can be called
G1 Z42

Cut sequence example

; absolute mode
G90
; move to piercing position
G1 F6000 X200 Y300
; lower torch until contact
PROBE
; incremental mode
G91
; retract to piercing height
G1 F3000 Z3.8
; start plasma (blocking until transfer)
M3
; wait piercing delay
G4 P300
; move to cutting height
G1 Z-2.3
; absolute mode
G90
; enable THC
M6 V110 T1800

; perform cut
G1 F2000 X350 Y220
G1 ...

; disable THC
M7
; stop plasma
M5
; resync z axis
M8
; incremental mode
G91
; retract torch
G1 F1800 Z30
; absolute mode
G90