Does GRBLHAL have a power-off save function?

[spxwh]

Does GRBLHAL have a power-off save function? Right now, all coordinates reset to 0 every time I power it back on. How should I configure this? Thank you.

[terjeio]

Does GRBLHAL have a power-off save function?

No.

How should I configure this?

Write a plugin that adds a shutdown command that saves the coordinates, and then restores them on the first homing after power on.

[Bharathk-Gowda]

Does GRBLHAL have a power-off save function?

No.

How should I configure this?

Write a plugin that adds a shutdown command that saves the coordinates, and then restores them on the first homing after power on.

what about remembering the executing line number in auto mode (running from SD card) during Power OFF and ON

[terjeio]

what about remembering the executing line number in auto mode (running from SD card) during Power OFF and ON

That is kind of tricky but should be possible to add to a plugin, you can hook into the grbl.on_file_open callback to reposition the file pointer and restore context. The tricky bit is how to stop the program so the context can be saved. Using a feed hold is not possible since in hold state: 1. only real time commands are acted upon. 2. context includes planner and step generator states.
But, it is possible to add new real time commands in a plugin - one could add one that let all planned moves to finish before saving the current context. Your next challenge will be how to get support for this command added to senders, which could be bypassed by the plugin claiming an input connected to a button. This button could even be the on/of switch itself if a relay, and some electronics, is used for physical on/off)...