how does re-homing in g-code work?

Hi

How can I trigger a re-homing in g-code?
When I used mach3 it worked with G28.1, but it seems to be different in linuxcnc

It sounds trivial, but I did not find in in user guide and searching forum or google didn't help either.

are you looking to just return to machine home position or wishing to rehome and reset the home positions

cncbasher wrote: are you looking to just return to machine home position or wishing to rehome and reset the home positions

the latter - ie touching the home swittches and resetting position. Like I can do it manually on the axis gui with the "Home All" button (confirming I want to rehome)

Hi

See also www.linuxcnc.org/index.php/english/forum...ies-par-lutilisateur , albeit it is mostly in French

AFAIK you cannot re-home from G Code.
The reason is that linuxcnc will reject the command if it is not in Manual mode, the same way as it will not jog unless in Manual mode.

You can prove this to yourself easily. Open Linuxcnc in one of the sims, axis_mm or just axis.
Take it out of estop and switch the machine on ( F1 F2)
Then open the Hal Configuration dialog and enter setp halui.joint.0.home 1 in the 'Test Hal Command' line edit box and press execute
The X axis will home
Then press F5 to bring the MDI tab to the front and try executing setp halui.joint.1.home 1 to home Y
You will get an error ' cant do that (EMC_AXIS_HOME) in MDI mode'

I expect it could be got around in the same way that jogging during toolchanges has been, by changing mode and then switching back, but the bottom line is that you should never need to do it during a program.

If you are homing to physical switches, then you have a problem with losing position that needs sorting out.

If you do not have home switches and home relative to the workpiece, then you need to use the offset systems instead.

regards

helig wrote:

cncbasher wrote: are you looking to just return to machine home position or wishing to rehome and reset the home positions

the latter - ie touching the home swittches and resetting position. Like I can do it manually on the axis gui with the "Home All" button (confirming I want to rehome)

is their a specific problem you are having , you should not need to re-home and reset to zero once the machine is homed , it could be your not switching between machine coordinates
and work coordinates , which is causing you to have to reset . once the machine is homed you can return to this position by issuing a G28

can you explain your problem

cncbasher wrote: can you explain your problem

No actual problem.
It's just that for whatever reason my machine might lose a step now and then which does not matter for my requirements. Yes, I know this is due to mechanical limitations and no software issue. Anyhow during longer g-code programs an occasional re-home would prevent positioning errors from accumulating.

But I understand from ArcEye's post it's not possible.

Thanks