OS X and Connecting to an GRBL board

Hi there,
New to Lightburn under OS X, but i have been using it during the trial period on a Windows Laptop (Win8.1 - Eleks CNC+Laser, Woodpecker 1.1 controller).

I can’t seem to get communication thru USB. Instead of AUTO or a COM port, my choices are 2 Bluetooth connections. I am guessing this is a very specific OS X problem, but if any one has a thought…


Which OSX do you have and which mac computer? I often only get the bluetooth option until I open up the “Devises” panel, choose the devise and click OK … then the USB connection becomes available.

Hey Jonas
OS X 10.11.6 on a 2014 MacBooKPro
I can see which port it wants to be thru the ABOUT THIS MAC under the apple menu. Right side of the computer is Port 11. I had a similar problem years ago on an older macbookpro using an Arduino. It needed an FTDI Driver, and then USB appeared as an option. Like to avoid more random driver foolishness though…

Thanx in advance

I mean the “Devises” panel in LightBurn. Is your devise showing up there?

There is a common and known issue with the OSX virtual serial port driver locking up, and blocking other drivers. Resetting the Mac (not just sleeping) will unlock the port.

This is a more permanent solution:

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Thanx so much for that Link. Not exactly my problem, but it reminded me to look for drivers for a 340 Chipset, then I found this link : (discussion about 340 Drivers and OS X)
which led me to this file on GitHub

OS X 340 Drivers

I had a chance to install and reboot, then sprint downstairs to test. All seems well, at least Y axis moved 10cm. I did have to delete and redefine a device, but then it allowed me to select a new USB port.

I’ll post more results when i get more of a chance to play…


BTW on the first link are instructions for removal of the driver, in case all is not well