@dc42
Is there anywhere to find documentation/discussion on RRF3 specs? and status of implementation on Duet firmware?

Thank you all for your responses.
Yes, I found that reply of M585 as well.
However, the definition and usage of M585 is slightly different from that of G38.
To my understanding, G83 is more like "zero this coordinate system to this point" and M585 being "confirm the tool is at this coordinate."
It should be possible to write a macro to use M585 to zero a work piece.

@dc42
I skimmed through the implementation of G32 and guess I can [try] implement G38.*.
I was wondering if there are any active work in progress, so I would like to open a discussion here first in case it is almost done.

@LB
I'm still learning as well
if you are cutting a feature on an existing piece, you will need to set the machine origin to match the origin of the piece in your CAD, say the bottom left corner of a block aluminum. By using G38, the machine can probe the edges of the aluminum block, and locate exactly where that bottom-left corner is. One can also do this by hand by jogging tool slowly towards an edge, but having the machine do it automatically is easier.

Are there any plans or work-in-progress to add support to G38.x command?
It seems to be an important feature for CNC users. e.g. to zero tools and more importantly, stock.
I saw some discussion but not sure if there were any update.