Adding a diode to Ruida machine

I’m trying to add a diode laser to my Ruida CO2 machine for lower-power engraving. Specs:

Ruida 6445G(EC) controller
100-watt Reci tube
NUBM44 diode laser
J-Tech Photonics high-current laser driver

The driver has very simple connections: power in (from its own power supply), PWM in and power out to the laser.

I know these are connected properly as they’re clearly labeled on the PCB itself:

I have the PWM in connected to pins 1 and 3 (LPWM2 and GND) on the CN6 connector on the controller.

I’ve enabled tube 2 in the machine settings, and it shows up in Lightburn. I enabled it in the cut settings and disabled tube 1.

I set up a simple test file that consists of four lines 10mm long, each set to cut at 2mm/sec and each at a different power setting so I could watch the diode and see if it was changing power with each different line like it should.

I get zero response from the laser. The driver has a setting to switch from PWM to constant 100% power and the laser works then but I get no response on PWM.

Is there a connection or setting I’m missing on the machine or in Lightburn? I noticed some PWM frequency options when I was enabling Laser 2 but did not adjust them.

Thanks for any help!

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