Max/min power in controller and in LightBurn

Can someone please explain to me how the max/min power settings on the controller (both set to 50 by default for me) interacts with the settings in Lightburn?

To be honest, I don’t even get what the controller settings do as they are set by default…

I’d have to double check my Ruida settings, but I believe ours are 0 and 100 min/max respectively. That sounds really strange that yours would default to 50 for both. That makes me think it’s only ever doing 50%, regardless of what you change in your LightBurn layer settings.

I agree, it doesn’t make sense, and I’m nervous about screwing around with it.

Also, how does it interact with power in Lightburn? Say that Ruida had 0% and 50% as min and max, and I set 50% in LB. Does that make it 50% or 25%?

In that instance I do believe that you’d be using 25%. I think LightBurn (or RDWorks) would just send their values, and the controller probably uses those as a percentage of the controller settings.

That’s my suspicion as well, because I find 60% in LB surprisingly weak, but if it’s just 30%, that explains it.

But, I just suspect, and I can find no documentation which proves it (or disproves it).

you guys are mixing up 2 different things, in the vendor settings (stored in the controller) you can set the absolute minimum and maximum power. What ever you set the power to in your software, RDworks or Lightburn the output will not be lower than the min or higher than the max set in the vendor settings.

You can set min and max on the display but these settings will be overridden by RDworks or Lightburn. On the other hand during a running job you can change the min and max previously set in RDworks or Lightburn (Still not below the MIN or above the MAX set in the vendor settings


Enno is correct. The min/max defaults on the controller are only ever used if you use the “default” power setting in RDWorks (LightBurn doesn’t even expose it).

So, the vendor settings are limits, not a “re-scale”? 50% in LB will be 50%, even if vendor max is, say, 70%?

The controller limit is determining the actual output limit. So if you have a 100W tube that the Ruida has a maximum of 80%, the tube will only output a maximum of 80W (actually it will be more or less, as it’s not perfectly linear).

If you set Lightburn to output a job at 50% in such a situation, it’s outputting 50% of 80%, or 40W.

Manufacturers do this for a few reasons - to improve the longevity of the tube and cut down on warranty claims, or to limit a non-adjustable power supply for the budget manufacturer that’s saved ng a couple of bucks everywhere they can,

In my opinion, it should be set to 100% and the PSU adjusted to give whatever figure the customer wants. In my case with my Reci W4, I cut more than engrave but want a decent lifetime for the tube, too, so I have my PSU outputting 28mA and my controller set to 100%. I could have it set to 30mA and use the 80% rule to allow me to overdrive the tube up to 130W if I need it, but I have a 150W for that, soon to be a 180W and maybe a 300W.

In the first instance, check what power your PSU is outputting compared to the specification of your tube, while you’re there, check that your PSU has a pot adjustment to change the maximum output.

Bo you are not right, the controller sets a maximum and if Lightburn outputs 50% it is 50% of the machine as long as it is above the set min and below the set max. Certainly not 50% of 80%

you can simply test that set you controller in vendor settings to 20%, start a job set to 30% max with rdworks or lightburn and let it run, if you pay attention to the job on the display of your laser you will see it will actually use 20% eventhough the layer says it wants 30%

Dear Anders that is exactly what it does

I think I understand but let me put a numerical value on it.
Lets say that the maximum mA capability of the machine is 100mA. If the vendor setting max is set to 60% that would equate to the machine never producing more than 60mA regardless of the layer power setting.
So, if the layer is set to, say, 50% the machine would output 50mA and not 50%of 60mA (30mA) as I think some are confusing. If the layer is set to 70% then the machine would output 60mA due to that being the max setting in the vendor settings.
Am I thinking correctly?

I think there’s enough confusion around this that it would be worth testing, not guessing. :slight_smile:

Lightburn, are you confused as well?

Not confused, I’ve just never actually verified which way it works.


I have ordered an ampmeter, will check when it arrives and I have enough spare time (have bought a new house, and have some serious renovation work to do…).

@LightBurn - I was thinking that since this is a support forum that the answer could be found here. With a user name of LightBurn, are you not a software creator?

I am, but I didn’t create the hardware or the firmware it runs. I know how to send the settings to the hardware, but I don’t know the exact way all those settings are interpreted.