2012 DSP Laser Firing on Reset/Power Down

[Gadroc]

I have the DSP up and running in my K40 conversion with the exception of one problem. Currently when I configure and wire the system to fire the laser on TL when I turn power off the DSP seem to bring the wire low and I get a laser fire, and if I reconfigure and wire for TH the laser fires while the reset button is held down.

Also I have the same power supply shown here, and my K40 came with the big resistor in series from the laser negative return. I've also replace the analog current meter with one of your 3 digit 100ma meters. In testing it only takes 30% PWM to get 15ma going through. Is that common or should I be changing any configuration or removing the return resistor.

[twehr]

I have the DSP up and running in my K40 conversion with the exception of one problem. Currently when I configure and wire the system to fire the laser on TL when I turn power off the DSP seem to bring the wire low and I get a laser fire, and if I reconfigure and wire for TH the laser fires while the reset button is held down.

Also I have the same power supply shown here, and my K40 came with the big resistor in series from the laser negative return. I've also replace the analog current meter with one of your 3 digit 100ma meters. In testing it only takes 30% PWM to get 15ma going through. Is that common or should I be changing any configuration or removing the return resistor.

I don't have this model controller (mine is older) but, if possible, you want to use TH - specifically for the fire-on-power-down issue you mentioned. As for firing on reset, there may still be a minor configuration/wiring piece that you don't have quite right. I know you need to use a different pin on the controller as well as moving the wire from TL to TH.

I believe someone else has mentioned the fire on reset issue. Search the forum to see if there was a resolution. It MAY be that, given this is a new board design, there is a design issue that needs to be addressed. Marco is in China now, working with the designers. So, if there is a problem, be sure to let him know so they can work to resolve it (hopefully in software update).

It is common for the PS to be capable of overdriving the tube. AVOID EVER GOING ABOVE 18ma. I went through 2 tubes before I learned to live with that rule.

On my system, I have 60% set as my max output and as a matter of practice, I don't go above 55% (17ma). For most materials, I try to run at 40% (12 ma). I try to do cutting at 50% when possible or the 55% if I must.

[Gadroc]

Thanks Tim. I'll switch it back to TH and contact marco on the reset issue. I read that thread before I got mine as well but for the life of me can't find it now.

Any recommendations on whether I leave in the limit resistor between the tube and the power supply return?

[Tech_Marco]

It's all about setting on the software. If you need to use TH, you need to configure the software for it. By default, it's set to TL

Marco

[twehr]

Thanks Tim. I'll switch it back to TH and contact marco on the reset issue. I read that thread before I got mine as well but for the life of me can't find it now.

Any recommendations on whether I leave in the limit resistor between the tube and the power supply return?

I took mine off when I converted it. Maybe having it there would help with expanding the virtual range of 0-60% to 0-100%. I have not tried it that way.

Another option for the 0-60 vs 0-100 is to put a variable resistor between the controller and the IN on the PS. Effectively splitting the controller's 0-5v PWM signal down to 0-3V. Once the sweet spot if found, lock down the variable resistor and be done with it.

Honestly, I have started moving toward using mA as my "target" points. That is always going to be consistent. I just do tests to get % vs mA points and then use those points for setting the output on jobs.

[Gadroc]

Tim,
I also use mA as my targets, just wondering why the range is so condensed on mine I only have 0-30% to go from 0 to 15mA. I've set the max power level to 30% to prevent it from going over 15mA as well.

Marco,
The laser fires properly when cutting and engraving when I've been configured both ways. When RESET was firing the laser I was configured in software as High Enabled and TTL on the DSP was wired up to TH on the laser power supply. When the laser fires on power down the software is Low Enabled and TTL on the DSP is wired to TL on the laser power. I will double check and try again tonight.

Also relative to the power settings Marco as your in china a nice feature would be to change the power settings calculation. Currently when you set the max power in manufacturer parameters it caps the PWM percentage, it would be nicer if it was used as a multiplier instead. This would be more consistent with other commercial machines.

Current it works like this:
PWM Output = MIN(Requested Power, Max Power Setting)
Example 1: Requested Power = 100%, Max Power = 30%, Real Power = 30%
Example 2: Requested Power = 50%, Max Power = 30%, Real Power = 30%

I'd like it to work like this:
PWM Output = Requested Power * Max Power Setting
Example 1: Requested Power = 100%, Max Power = 30%, Real Power = 30%
Example 2: Requested Power = 50%, Max Power = 30%, Real Power = 15%

[Gadroc]

Just got done verifying and firing the laser on TH has some bugs.

Steps I Did:
1) I rewired so the TTL output line on the DPS Laser 1 was moved to the TH pin on the laser power supply.
2) I opened manufacturer parameters in software and clicked read verified TTL level was at "Low level effective"
3) Updated TTL Level to "High level effective" and clicked Save
4) Clicked read and verified that TTL level stayed at "High level effective"
5) Restarted laser engraver and clicked read again to verify TTL level was still "High level effective"
6) Pressed reset and laser fired... if you hold down reset it also will take the PWM to 100% (my amp meter spiked up to 20 before I realized in just a few secs).

Basically when you have the DSP set to High Level Effective pressing the reset button brings the TTL pin high and maxes the PWM while the button is held. This is very bad and could damage equipment. I've moved it back to "Low level effective" along with re-wiring to TL on the power supply and reset works correctly, but I'm back to the laser firing on shutdown albeit only a 3-5mA quick fire.

[Gadroc]

Thanks Tim. I'll switch it back to TH and contact marco on the reset issue. I read that thread before I got mine as well but for the life of me can't find it now.

Any recommendations on whether I leave in the limit resistor between the tube and the power supply return?

I took mine off when I converted it. Maybe having it there would help with expanding the virtual range of 0-60% to 0-100%. I have not tried it that way.

Another option for the 0-60 vs 0-100 is to put a variable resistor between the controller and the IN on the PS. Effectively splitting the controller's 0-5v PWM signal down to 0-3V. Once the sweet spot if found, lock down the variable resistor and be done with it.

Honestly, I have started moving toward using mA as my "target" points. That is always going to be consistent. I just do tests to get % vs mA points and then use those points for setting the output on jobs.

I removed the return resistor and it didn't change the PWM input. For now I'll just deal with doing "more math", but as you said I've mapped out mA to PWM and use that anyways.

[Tech_Marco]

"Missing Fire" Problem duplicated. We're working a patch for it
In the mean time, please use "TL" output on PS and use Level Low on the setting untill the patch is completed

Marco

[Gadroc]

Excellent new Marco! I'm loving everything else about the board so far. Can't wait to be able to switch back to TH for laser, which will eliminate that last issue.

[dwessels]

I'd like it to work like this:
PWM Output = Requested Power * Max Power Setting
Example 1: Requested Power = 100%, Max Power = 30%, Real Power = 30%
Example 2: Requested Power = 50%, Max Power = 30%, Real Power = 15%

I agree, it would be great if this is something that was implemented.

[Gadroc]

Hey Marco,

Any status on the laser firing issues?

Thanks,
Craig

[Tech_Marco]

I just landed two nights ago. Before I left, the programmer said he was working on the TH issue. For now, he asked to use TL at this movment.

Marco

[Tech_Marco]

Craig:

Unfortunately, the TH is a hardware issue confirmed by the engineer. It can't be fixed until a new board launched with new circuit desgin. So the fact is that the board must be using TL

Marco

[Gadroc]

Ack!

Is there any recommendation on how to solve the laser firing when power is removed from the machine? Previously the recommendation was to switch to TH for laser control, but now that's not an option.

Marco you need to update the wiring diagrams and add some warnings to the store item for the 2012 DSP. This basically means in all setups the 2012 DSP has uncontrolled firing of the laser which is a BIG issue.