Took me way too long to figure this out on my Ender, so here's the short version for anyone fighting with it. First thing: the board almost always needs a driver. Most of these printers use a CH340 serial chip, and Windows doesn't always install it on its own. Grab the CH340 driver, install it, then plug the printer in with a decent USB cable (a charge-only cable will never work, this trips up more people than anything) and check Device Manager to see what COM port it landed on. Then in Cura, open the monitor section, hit connect, and set the baud rate manually to 115200. Auto-detect is flaky. If it says busy or refused, close and reopen Cura, and make sure nothing else like Pronterface or OctoPrint is holding the port, only one program can talk to it at a time. One more thing people miss: the printer has to be at the home screen, not sitting in a menu, or the connection gets rejected. And keep that SD card slot empty. If a card is in, the printer can act like it's busy and ignore your computer completely. Once it connects the first time it usually just works from then on.
How I finally got USB printing working - steps that actually worked
Oct 28, 2026
Last reply: 1 hour ago
4 Replies
First reply
My experiance lined up with most of this but the culprit on my Ender 3 Pro turned out to be something else entirely. I had the driver sorted and a proper data cable, and it still refused to connect. Eventually realized I was running the printer through a cheap USB hub so I…
Read the full replyMy experiance lined up with most of this but the culprit on my Ender 3 Pro turned out to be something else entirely. I had the driver sorted and a proper data cable, and it still refused to connect. Eventually realized I was running the printer through a cheap USB hub so I could charge my phone off the same port. Moved the cable straight into the back of the tower and it connected on the first try at 115200. Guess the hub was mangling the signal somehow.
I got mine talking to the computer last night after fighting with it for an hour, turns out my laptop was going to sleep and cutting the link every few minutes. Had to tell it to stay awake while printing. Now I'm nervous though, does the computer have to stay on and connected the whole time the printer is running, or can I walk away once the job starts? Seems like a long time to leave a laptop sitting there doing nothing.
To the fella worried about the laptop napping mid-job, yeah, over a cable the computer has to stay awake and connected the whole print. Lose the link and the job just stops. Back in my day we dodged all this by slicing the file, saving it to an SD card, and printing from the panel. No computer babysitting needed, walk away and let it run. That's still what I do for anything longer than an hour or two. The USB route is handy for sending a quick test or tweaking settings live, but for a real print the card wins every time.
Since we're talking about leaving computers running all print, I dug an old Raspberry Pi out of a drawer and put OctoPrint on it. Now the laptop's free and I can start jobs from my phone on the couch. Cost me next to nothing since I allready had the Pi. Even lets me watch a webcam feed to check the first layer's stuck down before I wander off.
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