@jay_s_uk said in Can I check output of pwm channel?:

I believe duex PWM pins need to be inverted.
If you use duex.fan6 and set it to on, does it turn off?

I believe this should help you
https://forum.duet3d.com/topic/17278/neje-like-laser-as-cnc-upgrade

No, that is the problem. It will only stay on. Will not turn off or change power at all.