New build. Confusion about wiring DLC32 v2.1 and 80w CO2 laser

Dear friends, I am in the process of building my 80w CO2 laser, and need some help.
I have collected most of the materials needed, currently waiting for the DLC32 v2.1 with a TS35 screen to arrive.

I need your kind help about wiring the system properly, already have searched a lot, but feel pretty confused as it seems there is more than one ways of wiring.

My LPSU is MYJG100W, and my tube is 80w. For the LPSU i have also the external LCD potentiometer. For the motor I have two nema 23.

Could you please give me any advice about proper wiring DLC32 with LPSU? Also if you have any suggestion about stepper motor drivers I would appreciate your opinion. I am mostly between DM542 and DM556 which look to have good price.

Thank you in advance!

These are the inputs to control the lps. The 5V output is not used in most places because of it’s low current limit, usually around 20mA.

Ground is common for all signals.

The IN signal controls the maximum current limiting of the lps. It accepts an analog dc voltage or a pwm, both are TTL (0 to 5V) signal levels.

Laser enable, when active allows the machine to lase. L goes low for laser enable, however the H input can be used as an inverted input for L.

Water protect needs to be low for the lps to lase… On my machine this is wired to ground and the controller senses coolant flow, if this fails, it will stop it’s operation.

The drawback to using P for coolant or door protection, is that the actual controller doesn’t know the lps is disabled and makes it’s difficult, if not impossible, to restart the machine after a simple coolant fault or a door being opened.

A dsp, like my Ruida and most commercial machines produce a pwm continuously while a layer is executing… When it needs to lase, laser enable goes active allowing the lase operation at the current limit value. Simply, there are two control signals, one for current limiting and one to allow it to lase.

Signal LPS
Current Limit IN
Laser Enable L
Laser Enable H
Water Protect P
Signal Ground G
DC voltage 5V

The problem is the DLC32 doesn’t have two signals, only one. This is because these are really built for digital devices such as an LED laser module, but the tube is actually an analog device.

The K40’s setup is setting the lasers maximum current, manually, from the front console control. They then use the PWM to toggle the tube on and off.

Monport has changed the the pwm with it routed to IN, so it’s actually controlling the tube the best it can by an analog control… However, I’ve seen some poor engineering changes that Monport has applied along with failure to actually test the machine after the engineering change and ship it to a customer not working.

So how you wire it is up to you… I’d suggest using L or P as a laser enable switch… Usually machines of this size will have a separate power switch for the lps mains. Using the pwn to feed and control the IN pin for software current control

Stepper motor drivers are usually newer if they have higher numbers… but I’ll included links to a pdf for each. You can simply read the engineering advances in one over the other…

DM542 pdf

DM556 pdf

Hope this helps – good luck


Thank you for your answer! I am not sure I understanding right what are you telling.

Do you believe this wiring diagram is right?

Thank you in advance!

1.Correct the mains input wiring.
2. ensure WP (water protect) goes through a switch to ground when you have coolant flowing.
3. PWM signal is positive, so it goes to H (active high) of the lps.

Other than that, looks OK…


Thank you again!

  1. Just mention that. For sure its better L goes to L, and N goes to N :smiley: . But dont think it will make any difference.
  2. Between P and G will go the flow switch and a button for ON/OFF of the laser tube.
  3. So the boards TTL pin goes to G and H, right?
  4. I am thinking to add also a test fire (push) button between L and G.

L is for Line and N is for Neutral … don’t think it makes a difference? :zap: … lol


Does it really matter when the current is alternating? Maybe I am wrong! If thats the case, please excuse my ignorance! Despite that I always look after that phase goes to phase, and neutral goes to neutral.

I believe so … however, correct me if I’m wrong…!

In the USA standard wiring, image is the ground symbol. Standard home wiring comes in with two 120V lines, requiring a neutral or ground return to get the 120V… If you switch them you could be applying full mains voltage to the chassis of the device, making it a high electrocution risk.

When you plug in a two pronged plug, one side is wider so you can flip them over… Note that in the diagram.

If you pick up 240V, then the neutral isn’t used.

Also notice System Ground (neutral), upper half and equipment ground.

Screenshot from 2022-03-14 10-36-52

Best solution.

Have fun


Thank you for your thorough explanation! I live in Europe, so maybe there are some differences. I know that a device works no matter how you plug it in the outlet. Maybe there are safety reasons that I am not well aware of, but as I said, I always look after that L goes to L, and N goes to N.

So, for the boards wiring, what do you think about the rest of the connections?

  • Between P and G will go the flow switch and a button for ON/OFF of the laser tube.
  • The boards TTL pin goes to G and H, right?
  • I am thinking to add also a test fire (push) button between L and G.

I really appreciate your help!

USA took half of Tesla best by using 60Hz, EU took the other half 240V

Not up on EU power grid…

Run the coolant switch from ground and P… when it closes it will allow the machine to lase.

PWM is only one signal, it can’t go to ground and H… just H

L is laser enable, not fire and it needs to held low… I’d suggest this go through a switch for laser enable…

The DLC32 only produces pwm output when it’s activating the laser. There is no direct pulse control on these.

Make sense?


Thank you for your answer. I continue to search because still I am not sure about the wiring. There are suggestions to use Spindles pin instead of ttls because of a v2.1 boards design flaw. Some uses only one cable from boards spindle (-) to lpsu L, and a common ground. My concern is if i am able to use power modulation using the software lightburn. There are also a wiring diagram that is with dlc32 v2.1 using FluidNC. Still investigate that.

If you want software to actually control the current values on your tube you have to run the pwm line into the IN input of the lps.

L should go through a manual switch to enable it to lase.

You are significantly complicating this. PWM is the only control line you have to control power and if you want to use it that way it has to drive the IN input.

If you can read a schematic, this is the pwm output of the DLC32. Chip on left is a voltage level translator from the cpu 3.3V to a 5V ttl level.

Red arrow is 0 to 5V pwm. If you go up to the yellow arrow, this is where you pick the pwm off at J18 – this drives Q1 pulling J7-1 (-spindle) to ground (green arrow). They are inverted signals.

When pwm goes high, setting the laser to 100% power, the inverted output pulls the L input low enabling it to lase at 100% power. I hope you can tell this isn’t the right way to drive the lps.



Make sense?


Thank you! I get better understanding with your help and this scheme.
I understand that S(from board) goes to IN(to LPSU), and TTL(from board) is common ground with G(to LPSU). I am confused about what pin goes to H(to LPSU).

You have to separate how these are wired.

One way you dial up maximum power with the manual pot on the console of the machine, the other way the software controls it.

The difference is digital one way and analog the other.

Your only way to control power is via the pwm, this is simply the only thing you have to control the lps current limits (power)

There is no laser enable for a digital connection, so I suggest you use a switch to ground. This allows you to disable the laser for setting up jobs… you can make a dry run watching the mechanics… Or just to protect you while working on the machine.

It is more easy to use L as it only need to go to ground, H has to be pulled up.

Make sense?