Saving GRBL GCode Settings for importation in UCCNC

[parsec (FerAS)]

Sorry to step in.
M3(CW) and M4(CCW) on the CNC is different than on the laser M3(fixed power) and M4(dynamic power).
You could try a Custom GCode machine wit more options to adapt to your CNC, remember to set Lightburn S-value max to 255 because your controller only accept values between 0-255.
Check also if you have some setting for the PWM frequency as lot of laser modules usually work at 1000Hz.
Maybe you could create a UCCNC profile for laser and other for CNC so you don´t miss any settings.

Also you could read the following topic

UCCNC and Lightburn

I worked with a stepcraft user a while back to come up with a method to generate gcode that worked for him. We arrived at using a Marlin profile but it’s possible your LinuxCNC method is better/easier. I hadn’t explored it. Take a look at this post: I believe you can achieve this by changing the Origin in Device Settings. If you only want to invert the Y, then flip the vertical position of the origin. For example, if it’s currently top-left, switch to bottom-left. If bottom-right, switch to t…

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You could try with your UCCNC laser plugin save the gcode of a small image and compare the output with the generated from Lightburn.
If the above solutions don’t work you have to save gcode and then edit with Notepad++ and auto replace commands per your machine requirements.