the "magic" happens in Duet
So its more easier to use with a slicer.
The Hotends are "parked" when in standby / not used.
; tfree0.g
; called when tool 0 is freed
;
; generated by RepRapFirmware Configuration Tool on Fri Oct 12 2018 16:15:59 GMT+0200 (CEST)
M83 ; relative extruder movement
G1 E-5 F3600 ; retract 5mm
G10 P0 R180 ; Standby temp = 180 degree
M106 S0 ; turn off our print cooling fan
G91 ; relative axis movement
G1 Z1 F500 ; up 1mm
G90 ; absolute axis movement
G1 S2 X-45 F6000 ; park the X carriage at -45mm
; tpost0.g
; called after tool 0 has been selected
;
; generated by RepRapFirmware Configuration Tool on Fri Oct 12 2018 16:15:59 GMT+0200 (CEST)
; Wait for set temperatures to be reached
M106 R2 ; restore print cooling fan speed
M116 P0 ; wait for tool 0 heaters to reach operating temperature
M83 ; relative extruder movement
G1 E5 F3600 ; extrude 2mm