After a year of using Lightburn and cutting many 100’s of jobs I’m starting to get the error :
“ALERT 3 - Reset while in motion. Grbl connot…” etc
The documentation says this means the laser is losing connection with my computer. However, nothing has changed in a year with any of the hardware after 100’s of jobs.
This now happens with almost every job I do, stopping the job and mostly wasting the material.
Some things I’ve noticed:
This has only started happening when I upgraded LB to version 1.7.04
It happens when the vertical axis gets quite high. Although there’s no friction at that point when I manually move the head back and forth so that might be a coincidence?
The USB cable has worked for 100’s of jobs and in very good condition.
TS2-20W
Windows 10
This issue is so bad and so prevalent it’s essentially made using my laser impossible to use. I have the feeling it’s not actually the connection (USB) that’s the issue.
Does anyone else have this issue and nailed it down to something other than a USB connection?
When you say the USB cable is in very good condition, are you talking about its appearance, or its internal shielding, its data transfer ability, the condition of the socket it is being plugged into, the driver it is using ? there are a lot of variables to consider even with something as simple as a USB Cable.
Appearance, the care it’s been given and also the over-the-top shielding it has. The laptop and port is in fantastic condition too and put away between jobs.
However I’ve not performed any direct continuity testing, shielding testing or data transfer consistency testing. This would likely be a massive headache to perform as the error fixes itself almost instantly. There’s no reason to think these problems have spontaneously started happening, although obviously wear and tear does happen.
It’s the same cable I’ve used for a year and 100’s of jobs, the same drivers, the same everything apart from LB version and Windows 10 updates. I very much doubt the windows update will have changed drivers.
The issue has only just started now and happens with 80% of jobs.
Consensus around here is try another cable. Rather than saying “it can’t be the cable”, test it. Just because something worked for years doesn’t mean it hasn’t failed now.
It could also be the power supply for the laser failing. Try running a job that fails consistently with power at 0. If it doesn’t produce the error, try again at 50% of normal power, then at normal power. If it only completes at low or no power I would say you need a power supply.
I’ve just tested the USB cable with my oscilloscope on each wire for continuity and it works just fine when the cable is put under a flex.
I’ve also tested the PSU when under a dummy load similar to that of the laser when under full power and moving and it’s also fine.
I’ve not yet tested the USB port on the laptop or laser.
This probably doesn’t mean anything. Digital signals require a wide bandwidth, so a dc check of them doesn’t really tell you anything except continuity.
We blame lots of out issues on usb cables, probably because they couldn’t manufacture them at any of a lower quality.
Keep in mind the USB is a very dependable communication medium. It implements a differentiated data path (twisted pair) that is very difficult to interfere with, as far as magnetic fields. Running it next to a stepper motor or other sources of emf should have no effect. This is against what most people advise on the Internet about usb.
If I look at this I keep in mind that assumptions have lead me down the wrong path many times.
So I suggest you take a different approach.
Since your console has no bad characters, I doubt you have a usb issue. If you look at the output after alert 3, it’s the firmware title. It doesn’t appear you have homing enabled on your machine?
Most likely you are resetting the controller some way, this causes an alert 3 and generally re-boots the controller.
This is usually occurring from a power loss or a brownout condition where the supply voltage drops too much to be tolerated. It can also occur with a failing usb connection.
It also advises that it occurred around line 0, that makes it a bit more easy to figure out as it’s usually referencing the first line of code. Also that it probably completed no code before the error.
However I’m not sure if I totally buy into either scenario mainly because you’ve done 100’s of jobs and all of a sudden you get errors. This sounds like a hardware problem → controller or power supply.
I’d suggest removing the plug from the head module and running the job a few times to ensure it’s working. If it works you likely have a supply issue.
If it still fails, might be smart to enable show all in the machine console window. We can then see what instruction it’s choking on.
That’s why I used my oscilloscope not a multimeter to check for signal integrity. The input was a function generator. As mentioned, I’ve already tested the PSU as well using a dummy load.
I’ll look into the GRBL further the next time, thx.
