Man, I’ve managed to otherwise “build form scratch” a 90w CO2 laser. It moves, its aligned. But I can’t get the laser to fire when hooked to the controller. Currently I have (Controler->PSU):
GRND->GRND
L-on->TL
PWM->IN
and I’ve looped the ground to the water protect.
I cant use the testbutton when the plug is in the PSU, but it tests fine when unplugged.
What am I missing?
It sounds like you are more than able to check this interface…
It looks like it’s correct and if I remember correctly if you unplug the Ruida from the lps you can fire it manually, which is what it sounds like you are saying.
I use LPS (Laser Power Supply) instead of PSU… most of these have a low voltage supply and the laser supply… PSU is not descriptive of either to determine which one they are referring.
Ensure P is grounded, that is the water protect… there is no need for the lps to be powered up, in fact I’d suggest you don’t…
Using voltmeter check the L-On1 (L) to see if it goes low when the laser is supposed to fire. You can draw a line, run it and see if the controller is telling the lps to enable… (L-On is the laser enable.)
You can check the LPWM1 (IN), at 50% power it should read 50% of the ttl voltage or about 2.5V.
So to clarify
The PWM will run as soon as it starts executing a layer, it only controls the laser current.
When it’s supposed to lase, the L (TL) input will go low, this enables the laser…
The only other control is the P input, that’s normally pulled low when active… if it isn’t low it won’t fire… Some of the lower cost lasers use this for water protect… most of the dsp units have an input (WP1) and will halt the machine… then it just wired to ground.
Make sense?
Might post a photo of the lps where we can read the connections …?
And of your diy machine… we eat that up around here 
Perhaps, in the controller configuration:
Water Protect Enable Laser 1 is True, but the WP1 input isn’t active (low)Enable Door Open Protect is True, but the DrProt input isn’t active (low)Laser 1 EnabledLaser 1 Minimum Power and Maximum Power setAll available through:
Edit → Machine Settings → Vendor Settings
So many possibilities! 
Thanks folks!
I must have missed the Laser 1 enabled 
I was just able to make my first test burn, It made a square! Now to tune in the software and focus!
The First Rule of Debugging: Is it plugged in?
The Second Rule of Debugging: Is it turned on?
Now the hard part begins …
And the 3rd?
Can you drive it?
@wrongcaptcha glad you’re up… speak up if you have issues…
Mark the thread the fix it as solved… 
Good luck