Unable to connect Mini (1) via USB

I’ve been successfully using my Lulzbot Mini on Windows 10 since January of 2018. A month ago, my desktop PC died, and I replaced it with a new one. (Still running Windows 10.) While re-installing software, I installed the latest (non-Beta) software from cura-lulzbot_3.6.20_win32.exe. Now, when I start up the user interface, it pauses for a long time (~1-2 minutes) at “Loading interface”, but eventually displays the interface. The printer is connected via a USB 3.0 port with a known good cable. (I.e., it was working before the PC upgrade.) The OS sees the printer connected on COM4 in the Device Manager. But, when I attempt to “Connect” in the interface, the console says it’s connecting via COM4 at 250000 baud. That pauses for a few seconds, then says “Failed to connect” (with no other error message).

I’ve tried uninstalling, cleaning files, and re-installing the software. I’ve tried going back to 3.6.15. I’ve tried using the software that originally came with the printer. I’ve tried three different USB ports. I’ve tried changing the hardware speed on the port, but it only goes up to 128000 baud, and there doesn’t appear to be a way to adjust that on the Lulzbot side in the interface. I’ve made sure that the USB drivers are up-to-date (at least according to MS). Another thread here postulated that the USB connector on the printer and/or the printer’s interface card “went bad”. Due to the timing of this failure, I don’t believe that could be the problem.

So, at the moment, I have a large, expensive paperweight and lots of unused filament. Anyone have a solution for me?

If there are special USB drivers needed, they would be included in the installation of CuraLE. You can try installing something like Pronterface which should also include any USB drivers if needed.

Personally, my TAZ 6 is connected to a Raspberry Pi and I use OctoPrint to communicate with it. I do have a USB switch so I can attach it directly to my Windows 10 desktop, but I don’t do that very often.

It’s in Machine Settings, Printer tab, all the way to the right.

Thanks for the info. That worked. Once. I then made the mistake of obeying the “Firmware update needed” prompt. After that completed (and I reset “Extrusion steps/unit” and “Z-axis offset” – or at least I tried to), I’m back to where I was before.

< [10:11:05] Attempting to connect to COM4
< [10:11:05] Attempting to connect to printer with serial COM4 on baud rate 115200
< [10:11:19] Can’t connect to printer on COM4
< [10:11:19] Closing the USB printer connection.
< [10:11:19] PrinterConnection.close: cannot join current thread (expected)

Yes, I’ve checked the COM4 settings to make sure it’s set to 115200. I guess I’ll try the “fix-all-problems” step of rebooting.

It seems that trying to match your baud rate with Cura software is meaningless. Mine is default set to 9600 and Acura’s default setting of 250000 and it works. Yes always gotta try the reboot. Let us know.

Well… I think I’m SOL. I tried rebooting, powering the printer down, resetting the port, changing to another USB port, and everything else I could think of. No dice. This is a new desktop PC, so I went to two of my other PCs, loaded the software, re-booted (to make sure), and … no dice. Same thing on all three systems, “Unable to connect”. Oddly enough, on one of them I selected “Update firmware” and I could see a light flickering inside the Lulzbot case, so something was happening on the USB cord. But could not connect either before or after the firmware update. I’m beginning to think it’s something in one of the latest Windoze updates. Thanks anyway for the advice.

I’d set the Lulzebot to use 115200 bd and try other USB ports. I normally run through a hub with USB2 ports. USB3 will renegotiate to USB2 theoretically but if you have trouble try a USB2 hub which you can check with a USB stick.
Also check the power settings on the PC, disable the power down feature for the USB ports, and check Google for USB port problems on your type of PC.

Woo-hoo! Something that worked! My new PC has 8 USB ports, but they’re all “black” which SHOULD mean USB 2.0. After digging through the documentation, I found that two are 2.0, four are 3.1, and two are 3.2. I had the cable plugged into one of the 3.1 ports. When I switched to a 2.0 port, it started working! (Although I probably should point out that the cable that came with the printer is 1.0 – white tabs on both ends.) Thanks, everyone, for the help and advice!