Implementation of M code control executable program

Use an executable program in a shell script and name the script M3. Can it be executed on linuxcnc? Or how can I use this executable program to make it an M code.

The M code uses an executable program to control the laser switch. The executable program is implemented by the laser control api. I want the M code to call this program. How should the M code be written?

Whats wrong with using spindle.0.on? It triggers on with M3 and off with M5

Thank you for your reply. I want to use M3 to complete the laser turn on, and M5 to complete the laser turn off, but it cannot be achieved on Linuxcnc. What do I need to do? There is no M3 in Remappable Codes (linuxcnc.org/docs/2.8/html/remap/remap.h...map:remappable-codes), what should I do?
thanks，
chen

You can use shell script in a remap. Here is an example file called 'M234' for a remap of M234:



The code will of course need to be adapted to your api.
This file is in a folder named 'mcodes' inside your machine config folder

Then you need to add this to the [RS274NGC] section of your INI file:


You can also use python for remap.

If you want to use M3 in your gcode you might have to call your custom M-code remap by connecting an MDI-command to the spindle.0.on pin:
and add this to the [HALUI]-section of your INI:

 

I thought M100 - M199 were not suppose to be remapped. I'm pretty sure that is in the docs somewhere.

Thanks bevins, I changed the number.