Different machines and controllers from same PC

Just ordered a Ruida machine and am going to upgrade my K40 to cohesion 3d laserbaord so I will have 2 lasers. Quick question before buy the cohesion upgrade.

Can I run 2 lasers off the one PC using lightburn? - Cohesion by usb (as it doesnt have ethernet) and Ruida machine by ethernet. If yes is it easy and quick to switch between machines and can they both be working at the same time?


You can have multiple device profiles defined and switch between them at will. You will not be able to “talk” to more than one laser system at a time. You can send a job to one, then switch profiles and send a job to another. Is this what you are wanting to achieve?

Yes it is as long as I don’t have to wait for the job to finish before switching profiles. Ruida stores the job so it doesn’t have to be streamed, does cohesion do the same?

I see also from another thread Multiple lasers, one computer that 2 versions of lightburn can be open at the same time. Can each lightburn version open talk independently to each controller at the same time?

Cohesion3D laserboard, or any other gcode controller needs to finish the job before you can switch devices. As you mentioned, with the Ruida, as soon as you finish sending to the laser, you can switch devices.

hmm so maybe it is better to get a Ruida controller for K40 instead so I don’t need to worry about having to wait for the cohesion job to finish before swiching jobs. Or get a 2nd computer

Two versions/instances can be open at the same time, unfortunately the two can’t talk independently. The first LB opened is the “master”. When you close that one, the second instance can start talking to the second laser.

Would be great if they could talk independently.

That’s only true if they’re trying to talk to the same laser, which isn’t the case here. Each instance can maintain a connection to a different machine with no problem.

C3D does not buffer the job - it’s streamed, so if you started a Ruida job then streamed a C3D job it would be fine from a single instance. Once the C3D job is started you couldn’t switch to the Ruida until it was done streaming, so a 2nd instance of the software would be more flexible.

I have two lasers (both networked) and two instances of LB. Only the first instance can talk.

If it should work. What am I doing wrong? I did get a Win 10 machine, hoping it was because of the Mac I didn’t get it to work before.

So to confirm I am understanding this right before I proceed with the cohesion purchase. Lightburn can communicate to each laser at the same time?

If I am using 1 instance of lightburn then I need to wait for c3d to finish before I can restart the ruida job. But if I just open another instance of lightburn then I would not need to wait for c3d to finish before starting ruida job?

I believe this is what you are asking.

Seems there is mixed answers.
-Grumpy_Old_Man saying it cant communicate with more than one at the same time.
-Patric confirming this and also saying he has 2 lasers and not able to communicate at the same time
-Oz saying you can communicate at the same time as long as 2 instances of lightburn are open.
-Also Oz on another thread here Multiple lasers - 1 computer working at same time - possible? (last post) says it can only communicate with one machine at the same time even though 2 instances are open

Thanks for the quick answers so far, hope to get a definitive answer.

Putting a Ruida on a K40 is like dropping a V12 into a Yugo.

There are better, cheaper solutions - let alone the problem of fitting it in the case, with drivers, etc. (you do realise you have to buy external drivers as well?)

Much better to a) buy a better machine with a DSP controller in the first place or b) use a decent controller with built-in drivers (or plug-fit SMD drivers) and ethernet.

The cost of a RuiDa controller is about the same cost as the K40, before you purchase drivers, etc.

I can see your confusion.

Patric was wrong, as evidenced by Oz’s correction.

You misread Oz’s post in the other thread - he made two independent statements:

“It’s also possible to run multiple instances of LightBurn on the same computer, with each instance connected to a different laser.” - so, two instances, talking to two different controllers concurrently.


“LightBurn will only actively communicate with one machine at a time, but with DSP controllers that buffer the whole job (Ruida, Trocen) you can send to one, then connect to the other laser and send a different file.” - in that paragraph he was talking about running a single instance, and connecting to two DSP controllers, consecutively.

Eleusis, if you stay with the standard K40 board you can run K40 Whisperer and Lightburn at the same time :slight_smile:

If you use a Windows PC. Otherwise, you can’t.

For us Unix and Mac OS users, it’s a lot easier to replace the awful M2 Nano controller with something more useful, and that supports PWM power control.

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There’s no mixed answer:

  • One instance of LightBurn can communicate with a single laser at one time, and maintains an active connection, so a second instance of LightBurn cannot communicate with the same laser as the first instance. A number of users will run a 2nd copy of LightBurn to prep a design while the first instance is running, then try to send a job to the same laser from the second instance. This doesn’t work.

  • Anthony (Grumpy) says you can’t communicate with more than one laser at the same time. This is correct. With a Ruida system, you can send a job to be cut and the machine buffers it while it’s running. Once the send is complete, you can pick a different laser and send a job to that one. If the laser you’re talking to requires streaming the job (like most GCode controllers) the connection has to be kept until the job is complete.

  • There is no issue communicating with multiple lasers using multiple instances of LightBurn, each communicating with a different laser, either via USB or Ethernet. On a Mac this is troublesome because MacOS itself prevents multiple instances of the same application from running, but that’s an OS issue, not a LightBurn issue.


You just need to create multiple copies - I use the ‘duplicate’ Mac OS function in Finder.

51%20PM 42%20PM

Yes, I’ve done that, and others have too, and it does work, it’s just a little odd that you have to. :slight_smile:

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It’s the nature of the way Linux runs apps.

I showed the easy ‘user’ way - you can run multiple iterations of a single app from a terminal session or a script:

open -n /Applications/LightBurn.app

Or (assuming you’re using Bash) ‘n’ iterations with:

n=5 ; for (( c=1; c<=n; c++)) ; do open -n /Applications/LightBurn.app/ ; done

So create a bash script and save it in your ‘applications’ folder, or add it to the app bar. Every time you click it, a new iteration runs.

The ‘n’ argument just tells Mac OS to open a new iteration.

Thanks for the clarification. I’m going with the C3D.