That is normal for devices using hardware such as FTDI, CH340 etc. which have their own specific drivers. However for serial drivers running on a microcontroller having it's own USB stack such as more modern Arduinos, the serial device uses a generic USB class called Communications device class (CDC) and specifically part of the Abstract Control Mode (ACM). This uses a generic serial driver and gives rise to device nodes called /dev/ttyACMxx. It's possible that eventually dedicated hardware will appear that also conforms to this model.
On Sun, Aug 2, 2026 at 4:59 PM Alan Perry via cctalk <[email protected]> wrote: > I missed the beginning of this discussion but I am using USB serial ports > (with a variety of USB-serial devices) on Ubuntu everyday in my day job and > the device files are /dev/ttyUSB*. I connect with putty. > > alan > > > On Aug 2, 2026, at 00:27, Torfinn Ingolfsen via cctalk < > [email protected]> wrote: > > > > To add to what Paul wrote: > > Here is a oneliner to check for usb serial ports on a linux machine: > > $ ls -l /dev/tty[ACU]* > > (the initial '$' is the prompt, don't include it in the command) > > run this before and after you plug in your usb serial device, and you > > will find it - if it is detected. > > > > If the device only works as user root, you need to create a file to > > set ownership, group and permissions on the device when it is plugged > > in. This is commonly done through udev / udevadm on linux. > > > >> On Sun, Aug 2, 2026 at 4:00 AM Paul Berger via cctalk > >> <[email protected]> wrote: > >> > >> Well the first thing to do is make sure the USB serial device gets > >> configured, when you plug it in, you should see the serial device listed > >> in the output from 'lsusb' and there should be messages about it in > >> 'dmesg' (requires root authority). It is possible that the naming > >> convention for the tty device that get created is different between the > >> two versions of linux. The usual way is the device gets created > >> dynamically when you plug in the USB serial device. on my linux, > >> Devuan which is debian based but unencumbered by systemd, it creates a > >> device /dev/ttyUSB0 most modern distributions I have seen use names like > >> this. > >> > >> Paul. > >> > >>> On 2026-08-01 21:41, Jon Elson via cctalk wrote: > >>> Well, everything is a fight! > >>> > >>> The project I'm working on is to get a VMS MicroVAX system working at > >>> VCFMW. The plan was to have serial comm on a Linux laptop connected > >>> to the MicroVAX. I have the serial comm working on a Dell desktop > >>> machine, so I just plugged the same USB serial cable into the laptop, > >>> and NO COMM! I plugged back into the desktop, and serial data works > >>> fine! I'm totally mystified! The desktop is running an OLD Debian > >>> kernel (7.11), the laptop is running a late Ubuntu (24.04.4). > >>> > >>> I have no idea why the laptop doesn't communicate. I have tried > >>> minicom, picocom and cutecom, same result on all of them. > >>> > >>> Thanks for any help you can suggest. > >>> > >>> Jon > >>> > > > > > > > > -- > > mvh > > Torfinn >
