Using Marlin 1.1.9 the probe calibration as detailed at
Marlin Read.me is incorrect.
I have tested the sensor and can confirm that it works, however, the
steps to calibrate do not work.
This is because when executing the G28 command to home the bed, in order to establish the Z_OFFSET, the printer uses the hardware endstops connected to Z_MIN and therefore the Z_OFFSET is based from the Z_MIN endstop rather than the probe connected to Z_MAX.
The read.me states:
Quote
"Unlike suggested in geeetech.com/wiki/index.php/3DTouch_Auto_Leveling_Sensor, the existing end stop switch is expected to be kept connected to Z_MIN. So, the sensor is to be connected to Z_MAX, according to Marlin's default settings. Furthermore, GT2560-A+ provides a connector for the servo next to thermistor connectors (see GT2560 and GT2560-A+)."
Also, software endstops need to be disabled in Marlin to allow negative Z values to be entered, using
M211 S0 Z0
Is there a G-Code that I can enter to instruct the printer to use the probe as the end-stop temporarily to enable me to assess the Z_OFFSET. I have tried G30, but the output from that seems incorrect as it gives Z4.0.
If someone can help, I will provide a pull-request with the correct configuration guide.
