UCCNC & Laser Problem

[BigAl]

Hi together,

I played a little bit around with the settings of UCCNC (using the UC100) to find out how to control my laser. Don't worry. I only checked the signals. The laser is not connected .

The laser is controlled by PWM in the following way:

- Static 0V is 100% power
- Static 5V is 0% power
- All in between is the ration of the PWM signal. E.g. 50% duty cycle means 50% power.

So far so good. I set the output of the laser (Laser pin) to a free output pin, active low and measured the signal with my oscilloscope. As long the laser is off, the output shows static 5 Volt. When the spindle is on I'm able to control the laser output with M10 and M11. If I set for example the the laser to 50% (M10Q128) I get a signal with 800 Hz and 50% duty cycle. Up to here everything works correct. But here comes my first question:

How can I set the frequency of the signal? Is the 800 Hz fix? I like to set the frequency higher for better resolution.

Then I tried the "Laserengrave" plugin. I made a white picture with a Black vertical bar in the center. I expect, that the machine will move through the picture line by line and switch the laser on at the black area. This works so far, but the output is all the time 100%. If I use gray scale it is modulating. This is ok but I'm not able tho control the overall power. If I use gray scale the power is modulating in the range from 0% (White) to 100% (Black). Therefore my second question:

How can I set the overall power of the laser output? The plugin allows only setting the Feedrate but not the maximum power.


Ok. The second question is solved. There are sliders below the image in the Laserengrave plugin to control the output power. I didn't realize that .

That's it for the moment. Thank you for any answer.

Alex

[cncdrive]

The PWM frequency is fixed. You can't get a better resolution, it is 256 steps on the fixed frequency.
I'm not sure if it is really 800 Hz, I mean if your measurement is correct or not, probably is, but that means 800Hz -> 0.00125sec time for a full cycle and 0.00125/256sec = 0.0000048828 or 0.0048828 milliseconds or 4.8828 microseconds for the one step resolution.
The frequency for that is 1/0.0000048828 = 204800 Hz.
Don't expect that any chinese laser controllers can switch the laser even that fast, so the bottleneck will be the laser controller not the PWM frequency.

[BigAl]

Thank you for your answer.

The frequency is (about) 800 Hz:

SCR02.PNG (8.12 KiB) Viewed 4733 times

(M3M10Q64)

But you're right. Finally it depends how fast the output reacts to M10 and M11. This I cannot measure because I do not know what's going on internal the UC100. For a good resolution I have to play with the axis speed and the laser-power. There are two situations where it is interesting. As long I make cutting it is not so critical. In this case the laser switches on and stays on until the cut is finished. The critical thing is only engraving. I will check this as soon I have the laser in operation...

Regards
Alex