There was a problem sending data to the laser

I see that I may not be the only one to observe this in LightBurn. My laser is connected via network cable to my home network. LightBurn is running on my MAC (connected via WiFi to my network). What I am about to describe worked flawlessly in the past. I am cutting some pretty large sized invitation cards (lots of frilly detail, all cuts, no images or filled areas) on 19" x 25.5" cardstock (3 per sheet). Anyway, after the job finishes, I prep the next sheet and hit the “Start” button and get the titled error. I have tried resetting the Laser (power off/power on, Esc key on Laser, and Reset Button on Laser) which doesn’t seem to have any effect. I have tried the “control click” or Right Click thing and it says Found RDC644XS but still seems to think the laser is “busy”. I have used the positioning tool and the laser responds but still reports the error when I click Start. Closing LightBurn and waiting a few minutes seems to “fix” the problem at least for one more job but I really don’t think I should have to close the program and wait for a period of time for the software to begin talking to the controller - as I mentioned, running one job after the other worked flawlessly in the past. This really has me puzzled. Not sure where to start looking.

MAC is running Mojave 10.14.6, LightBurn v0.9.07.

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Well, for what it’s worth I think the job is somehow leaving the machine paused. Tried several other combinations and surprisingly, hitting the pause/run button on the controller forced or allowed the job to be accepted. In any event, because I had a second set of cards to cut (much more simple job) I loaded that one in LightBurn and sent it up to the laser with no issues. I suspect this is related somehow to the size of the job. I would be happy to send the .lbrn file to see if anyone can reproduce. Let me know.

Thanks @Sparkman for reporting this. Yes, this would be helpful. Please send the file and reference this post to support at lightburnsoftware dot com and we can take a look. :slight_smile:

I just sent the file. Maybe you can figure it out.


OK, just had it happen again (with a different file). Tried a bunch of different things (all previously mentioned) to resolve the issue and came up zero. So, I saved my work and created a new file. Drew a small square and sent it to the laser. It sent and cut fine so I opened the file I previously saved, sent it to the laser and it started cutting just fine. I don’t know if this is a communication issue or what but it is pretty frustrating. I guess I could run wire-shark or something to see what is going on, but this isn’t exactly my area of expertise.

Mine does the same on same controller connected to run over network, except I’m using a PC. Mine goes like this:

  1. Send job to laser, laser runs job fine.
  2. reload next piece of material, send job to laser, get “busy” error after 30 seconds or so.
  3. send job to laser a second time and it runs like nothing happened (occasionally this doesn’t work, so I reboot everything and start again).

Unfortunately this happens every time I’m running multiples of same project, but I’ve gotten so used to this behavior I’ve never reported it(and I’m usually busy working, haven’t felt like tinkering). Knowing this happens to others makes me more interested in finding a solution. It usually only loses me 30 seconds here and there, but if it can be fixed that would be great.


This has happened to me also, but not often.
Send a job and run it. When it’s done try to send another job and once in a while I get the “paused or busy” error. Right clicking “Devices” returns “ruida controller found”, but usually it still says paused or busy and I have to restart the laser to get it to play nice again.
LB0.9.07, Linux Mint, computer and laser both hard wired to the router, no wifi.

As long as you aren’t changing anything and are just running the same job over and over again, when the job finishes, hitting the “Start/Pause” button on the controller will run the job again. But this won’t work if you power down the laser or hit the Reset button on the controller.

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That’s good to know, honestly I rarely mess with the controller interface itself other than when I first set it up or when I’m aligning mirrors. Thanks for the info!

Thinking about this more and some of the comments above, it’s like the machine disconnects from the network, or goes to sleep on the network during a run. Sometimes I also right click and force a machine re-connect and that works. I guess once the file is sent and the machine is running there’s no reason to stay connected, but no reason to disconnect either. Odd…


Well, it doesn’t go completely to sleep - while in this state, I have seen it respond to the stop button in lightburn (the controller beeps) and the move to position button (the machine moves to the correct position) so, at least for some functions, it is clearly communicating via the network. Next time this happens, I will try to see if it responds to a ping. I guess I am going to have to break down and install wireshark to see what is going on. As I mentioned earlier, it happened again yesterday with a much smaller project so I don’t think it is related to the size of the job and running a different job to the laser seemed to clear the problem.

Our relocation is ‘finished’ as of yesterday - we’re in our new location and I’ll be getting equipment set back up again over the next week or so, and should be able to start digging into this soon.


I’ve had similar issues with connection errors over the network. But, it is usually for the first job I send. Once I get it going, there isn’t a problem. But, once in while I do. I usually get it going again, but different

Did you guys get a chance to look into this?

So far I haven’t been able to reproduce it here. I’ve tried two different controllers (3120 and 708c) and both USB and Ethernet. None have produced the described issue, so there has to be something different happening on your end that isn’t on mine, but I’m at a loss as to what.

If you have a sequence of steps that will faithfully (even occasionally) make it fail, that would help.

Mine is constant. Start everything and connect, send job to laser, laser runs, laser completes job and stops. Load a new file, send to laser, nothing happens. A few moments later I get the error message “There was an issue sending the job to laser, machine may be busy or paused.”. Sometimes “disconnected” shows up on the laser tab. If I try again around 50% of the time it runs, fine 2nd try, 50% of the time I have to take further measures (right click on the devices button one or more times, occasionally reboot everything). Reset on machine itself doesn’t seem to do anything. I’m on Ethernet, have not tried on USB. My machine has a Ruida controller (6442 I think), connected to the network via a network extender which is on my network. Running Win10 machine connected to the network via WiFi. The issue isn’t stopping me from running anything, but it’s pretty annoying. My typical job lengths are pretty short, 4-10 minutes. It to me at least still appears as though after the job is sent the connection just goes to sleep. The other commands like frame also don’t work when in this state.



As I reported earlier, this seems to be an intermittent problem and as a programmer myself, I understand how that sounds and how it is nearly impossible to run down. I don’t know if running a packet analyzer would expose the root cause of the problem but I would be willing to try and send you the result - assuming I can get it to fail again. I noticed this on my MAC and I have run at least two system updates since I first reported this. I have some jobs to run this week so if it fails during those jobs, I will install wireshark or something and see if I can at least capture the communications between my MAC and the controller for you guys. If it doesn’t fail, I am at a loss.

Circling back to this - Have you noticed if there’s any pattern to this that might be using jobs where one of the early layers in the job is disabled? The file you sent along has the outline layer turned off, so I’m wondering if that’s related somehow. I’m doing some tests now to see if I can narrow this down.

I’ve started experiencing the same issues as posted above over ethernet connection (via wifi) on a Mac running Catalina 10.15.1 and the most recent version of Lightburn (issue also on the last version).

Sometimes I’ll do certain parts of a single design individually on a single piece of work (by enabling cut selected graphics) so I might run 4/5 small files to make up a single design.

The first run always works. Then once I’ve selected the next part and try and run it I get the same error above. I’ve tried all sorts to see what it might be.

On the controller, the job timer actually starts counting but the head doesn’t move.

Stopping and esc the job on the controller clears the timer and puts the laser into idle.

Then its repeated errors. If I stop the job (timer running, head not moving) and press esc it, then press start again it starts the last good job over again.

Usually at this point I just plug in via USB.

Ruida 644XG.

I’m suspecting that it might be related to the ‘Cut selected’ or turning off certain layers. I noticed a difference in the cut files between RDW and LB when looking into this a couple days ago, and have corrected that, so it’s possible this is now fixed.

WiFi may be part of the issue as well. Ruida uses UDP for Ethernet transfers, which does not guarantee delivery of data, and there is no mechanism to retry. You can now change the timeout to be longer than the default (in the Device Settings) which can help, but ultimately using a WiFi network will have more failures. A wired Ethernet connection is almost flawless because packets won’t get dropped unless your network is nearly saturated, and that’s really unlikely these days.