Unsolved Stall/freeze when firing laser

[CreatieHallen]

He All,

We have been using the Duet3D platform for years on multiple machines, and it has been great.
Now we have hit a bump with a seemingly malfunctioning Duet3D. We purchased it from ReprapWorld, and they have advised us to seek help here, and figure out if it is a garantee issue.

Machine: A big laser cutter 900x600mm, most parts have been upgraded over the past years.

RepRapFirmware for Duet 3 Mini 5+ version 3.4.4 (2022-10-20 16:18:28) running on Duet 3 Mini5plus WiFi (standalone mode).

What works: When the machine starts, it can home, and start a job all fine. Controls work over the WiFi and we have built our own controls that use the API, both function fine untill it freezes. It has also been fully functioning for the past year, with the same config etc.

What fails: As soon as the laser needs to fire in a gcode file (G1 with an S value), the machine freeze, seems like it complete restarts.

Looking in the log saved to SD card data (M929), there is nothing to go on. The status after reboot shows:

Last reset 00:09:08 ago, cause: reset button

What we have already tried:

• Different SD cards
• Update to the latest firmware version
• Different gcode files, with different shapes etc. (all with the same result)
• Checked the wiring
• Checked the power supply
• Tried to connect with YAT (but it keeps saying: "warning: 5 bytes already buffered but not sent anymore")

Here is the config used: config_share.g.txt

Really hope that anybody can come up with something we can test or do, or explain how this could indeed be a fault in the hardware.

Thanks again! Cheers,
Kosmo - de CreatieHallen

[o_lampe]

@CreatieHallen The config looks OK, although I'd put the laser pin-definition earlier.

I suspect a brownout/shortcut of the 5V onboard being the cause for the reset. I recommend a serial resistor in the laser-fire wire to reduce max current. (not the laser current but the fire pins current)

[dc42]

@CreatieHallen I agree with @o_lampe, it's most likely an issue with power or a transient when the laser fires. Possibly a ground transient. What type of laser is it, and how is it powered?

[CreatieHallen]

@dc42 The laser is a CO2 tube powered by a MYJG100W high voltage power supply.
The power supply powering the tube is near to the only reaming part of the original machine, it has been functioning well for the past 5 or so years.

@o_lampe we will try to add a 1k resistor (or is another value recommended?) in serie with the control wire coming from the Duet. And hopefully it will do the trick. Is there a reason that this could be needed all of a sudden?

[o_lampe]

@CreatieHallen said in Stall/freeze when firing laser:

Is there a reason that this could be needed all of a sudden?

5 years of service is a long time. I wouldn't be surprised if the powersupply starts to show funny behaviour.
If the laser powersupply has a shortcut in the fire input, the Duet board will survive, due to the resistor. 1k is OK.