Host sends relative moves for extruder (in the case you use the extrusion buttons), so the sequence looks like:
G91
G1 E10
G90
you also can do it by
G92 E0
G1 E10
if you just send G1 E10 you dont know Extruder position and in best case it works once , any further
sending does nothing as Extruder is already at position E10.
f.e. if Extruder is at position E100 at the end of print and you send just G1 E10 it will retract 90mm and
if Extruder is at position E2 at end of the print it will extrude 8mm.
So extrusion command needs either G91 (switching to relative positioning) G1 Exx(extrude) and G90(switch back to absolute positioning) or G92 E0(set extruder coordinate to 0) G1 Exx (extrude)
