Marlin ver bugfix 2.0.x.8cfcabe
Repetier v2.1.6

I home all with G28. Z_AFTER_HOMING is set to 30mm
I then run this script

g0 x50 y50 ; place XY on bed
g28 z ; home Z and raise to 30mm (Z_AFTER_HOMING)
g0 z0 ; Z=0 = measure offset

It goes to x50, y50
then homes Z which ends up at Z=30mm
then it move Z to 0 to test my offset which is set at 0.20mm

Repetier Log
20:23:54.770 : N79 G28*45
20:24:03.945 : X:0.00 Y:0.00 Z:30.00 E:0.00 Count A:0 B:0 Z:24000
20:24:11.405 : N80 G0 X50 Y50*16
20:24:11.405 : N81 G28 Z0*96
20:24:11.405 : N82 G0 Z0*89
20:24:21.634 : X:50.00 Y:50.00 Z:30.00 E:0.00 Count A:20000 B:0 Z:24000

So why is Marlin saying it is still at Z=30? The probe actual position is about 0.10mm from the bed. (paper thickness)
If I click Z 1 + step, Z rises to 31mm.

21:01:42.183 : N100 G1 Z31 F1000*54

Edited 2 time(s). Last edit at 05/22/2020 10:35PM by ruggb.

And the answer is RH is forgetting it issued a G0 Z0 command.
The script runs and sends all commands. Marlin answers with position info only for a G28.
RH gets that and sets the position at Z=30 = the Z_AFTER_HOMING but it is at Z=0 from the G0 Z0 command.
RH sends a 1mm step, but does it absolutely and therefore sends G0 Z31.
A work around it to send an M114.
If the commands are sent manually then the position is rcvd b4 the G0 Z0 is sent and RH is happy to report the position as Z=0 after G0 Z0.
.