Call O Codes from hal signal

I am starting to learn for subroutines. I finished one mill tool-change with Ladder. My next project is tool-change with axis movement positions. I think subs will be the best choise, fix me if i am wrong.  i cannot find some very obvious staff.. 

My first question will be can i start subroutines with signal from Hall in Auto mode

Thanks a lot 

Yes you can take a look at

HALUI:

halui.mdi-command-XX bit in

halui looks for ini variables named [HALUI]MDI_COMMAND, and exports a pin for each command it finds. When the pin is driven TRUE, halui runs the specified MDI command. XX is a two digit number starting at 00. If no [HALUI]MDI_COMMAND variables are set in the ini file, no halui.mdi-command-XX pins will be exported by halui.
 

You might need to remap your O Word to a user Code first. But after this it's no probem

linuxcnc.org/docs/html/config/ini-config...l#gcode:ini-features
linuxcnc.org/docs/html/man/man1/halui.1.html
linuxcnc.org/docs/html/remap/remap.html

Cheers 

Patrick
 

Great start for me, I will make this on machine and test it how is working

Thanks again anfänger