First let me apologize for bringing this topic back up… it is listed in almost every category except for Snapmaker. I’m sure it’s more a windows/computer issue, but I am unable to fix the issue and no other posts on the forum have definitive fixes.
So here we go:
Snapmaker A350T with quickswap kit
40w diode laser
GRBL-M3 (1.1e or earlier | GCode)
s-value max 255
baud rate 250,000
Transfer mode Buffered
Firmware 1.18.2
Lightburn 1.7.08
Windows 11
USB Cable to Snapmaker Com port
Background. Two days ago everything was working fine and I should have left enough alone, but I was trying to dial in my Z height and was having issues. Skreelink had posted an update to his Snapmaker setup so I figured, I’d give that a shot and see if it rectified my Z axis issue. After following the guide, I couldn’t connect so I disconnected everything, shut down the computer, shut down the Snapmaker and restarted the whole system. When everything came back up I got the “Port failed to open-already in use?” error. This is where I went down the rabbit hole to figure out what’s going on… I’ve tried the following:
Updated the COM driver
Deleted COM3 (the port mine usually connects to)
Reinstalled COM3
Deleted devices in lightburn
Rebuilt my laser configuration
Rebooted everything
Verified that COM3 was connected and active in device manager
Selected COM3 from dropdown in Lightburn
“Port Failed to Open-Already in use?”
The weird thing is that everything worked a couple of days ago. I’m not sure what I’m missing. Anyone have any ideas or know of a sure fire way to get rid of this issue?
I did read someone had success reinstalling Lightburn, but if that’s the case, there should be something that can be done on the user side short of reinstalling.
Appreciate you all taking the time to read this wall of text.
Ok, got it to work again. Posting here in case it helps someone out. What I did.
In Lightburn, delete the device that wont connect and click ok.
In dropdown select the (choose) option (not the COM port)
In Device Manager (windows) click view → Show Hidden Devices
Find the COM port causing the issue and delete it.
Restart your computer
Reconnect your USB cable to the Snapmaker this will cause your computer to reinstall the COM port again.
Reinstall the correct COM driver (grab from Snapmaker Wiki)
Restart Computer
Restart Lightburn
Make sure your computer is connected via usb to your computer
Click Devices in Lightburn
Click Find My Laser
Lightburn should connect to your laser and find it (it did for me A350T - picked GRBL M3)
Complete configuring your device as needed.
Woot. Back up and running. Hope this helps someone figure it out as well. I know other lasers running into the same issue. Maybe this solution might help as well.
I would be interested to know if you could actually just delete the device in lightburn and then click Find My Laser and bypass all the rest. If I have the problem resurface, I’ll definitey try it and post back here.
I’m not 100% sure, but when connecting to USB, Windows creates a virtual COM port. It will use the next COM port in order that the system is not currently using/mapped. At least that’s how it has functioned for me in the past. Currently my computer has 2 virtual COM ports (3 and 4). When I delete 3, it recreates 3. When I delete 4, it recreates 4. If I delete both, it recreates 3 first and then 4 second. Again, I am not 100% sure, but this has been my experience since Windows 8. But you do bring up a good point, if you are uncofortable with any of the steps, I would defitely put in a support ticket.
I have used both M3 and just plain GRBL. When this problem presented itself, it was using the straight GRBL configuration. Talking to Skreelink (Snapmaker Guru), he suggested sticking with M3 as he has seen issues with connectivity using anything but the M3. It is also weird, that Lightburn itself recognizes the A350T as the M3 version as well.