Laser Setup UC300

[Delco]

I have a UC300/UCBB setup I am trying to get the laser to work on .
I have set pin17port3 for the laser ttl output , tested laser by applying 5V to ttl and it fires fine.
I have a relay for 12V power to the laser through a M3 command.
I have no other settings defined in the spindle setup tab other than spindle relay output enabled.

When I run this code I only get a faint laser maybe 1%
S255M03
M11
F1200.0
G00X0 Y0 Z5
G1 Z0 F400
M10Q255
G1X-75 F400
M11
G00Z5.000
M09
M05
G00 G53 Z0
M30
%

I assumed from the limited literature that Q255 is 100% power , I seem to be getting no ,measurable voltage at output 17 ?

Do I need to make any other setting change to get this to work ?

[cncdrive]

The UCBB has NPN output and if your laser control board has no pullup or too weak pullup resistor then it cannot sink eough current to properly switch the output.
You might want to add a pullup resistor to between the laser input pin and the laser's +5Volt power.
Also don't forget to common the laser's 5V Ground with the UCBB's ground.

[Delco]

So when you say pullup resistor you mean put say a 3K resistor between the output pin on the UCBB and the 12V supply to the laser or the earth to the laser ?

[Delco]

I went out in the shed and did some testing , a pullup resistor helps BUT with limited resistors around I tried a 10ohm , 300kohm and a 120ohm setup - all got the laser to fire , would not say either end of the spectrum is a success though.

With any pullup the laser still has some firing energy when a M11 is called so I get lines between the actual firing lines ,and at lower power levels it is a wide dot pulse.

Is there a way to increase the frequency of pulse so I get a consistant line but faint ?

And a way to remove power when a M11 is called - maybe add a M5 to the M11 and then a M3 to the M10 ? each time ?
It also does not seem to be reducing power when slowing down to do the letters ( feed is set the same but it naturally runs curves slower ) so they are not so dark ?

[cncdrive]

The M11 fully removes power, so I don't know why your laser is still firing.
Can you measure the Voltage on the laser input after M11?

And no, power is not reduced when doing letters, there is no such functionality implemented yet, however it is planned that we will implement it, I just did a discussion about this with the Vectric developer guys as they implementing this feature to their CAM products and wants UCCNC to support it.

[Delco]

Maybe I have it wired wrong , I have the 12V power for the laser activated by M3 through a relay on CN2_17 , then TTL activated from CN1_17.

So laser power comes on as soon as the intial M3 is called ,
I have the resistor between the power to laser and the TTL to laser at the laser connector plug .

So in effect there is a small voltage applied to the TTL wire at all times .

I tried the dropping resistor to earth but it seemed to do nothing ?

[cncdrive]

When does your laser turn on? When the TTL input is low (0Volts) ot high?
If the pullup resistor is the issue that it produces some Voltage, I mean it is possible, then you could try an output from the UC300ETH-5LPT pin directly, those are TTL push-pull outputs, so with those you do not need a resistor, because they can sink and also source current, however they can output only 0/5Volts, so do not try to pull that output to 12Volts, because that will damage the output of the UC300ETH-5LPT. But you do not need to pull that output on anyways, no need for any resistors.
Just one more thing is that if you will do this then you will have to common the UC300ETH-5LPT ground (5V power ground) with the laser controller ground, then you can remove the UCBB ground connection to the laser.

[Delco]

Thanks putting the TTL straight to pin7 Port2 direct to the UC300 worked perfectly , laser now working as it should and all M10/M11 functions work fine

[Battwell]

ttl level would be 5v
so the pull up resistor should have only been to 5v+ not 12v
probably!

[cncdrive]

Yes, to 5Volts it could be pulled up, but there is no need to pull it up, because those are push-pull outputs.