G28.1 means “store the origin position that the machine goes to when the {G28} command is issued”.

This position is stored into memory, but is lost if the machine is reset. You can make that position permanent by sending the M500 G-code.

The command is used as such :

G28.1 X10 Y10

Which means : record the origin position as being at the X position 10 and Y position 10

This G-code sets the origin position that the G28 G-code goes to.

And you can use the M500 G-code to save this position into the config-override permanently.

These resources are used as references for Gcode :

• LinuxCNC Gcode list
• Reprap Gcode list