If you allow me to talk from memory and a very little digging in my Web Browser Archives, may I say you are very right for looking into this. First, below is text copied from an ATMEL Application Note PDF file without a number, but with the shown title. There are many others like it on the same topic. USB Microcontrollers Application Note Migrating from RS-232 to USB Bridge Specification Doc Control Rev Purpose of Modifications 0.0 Creation date 1.0 updates Date 24 Nov 2003 22 Dec 2003 References • Universal Serial Bus Specification, revision 2.0 • Universal Serial Bus Class Definition for Communication Devices, version 1.1 • USB CDC demo firmware Abbreviations • USB: Universal Serial Bus • CDC: Communication Device Class • ACM: Abstract Control Model • VID: Vendor Identifier • PID: Product Identifier The Arduino shows up as "/dev/ttyACM(X) when attached to Linux via USB, and behaves just like a terminal port. It does not have all 8 serial lines active , but does use 2 simulated flow control lines to switch the Arduino into program mode. Going further to confuse and encourage you, "Bluetooth" wireless devices were originally invented to remove the wires of the PC serial ports. And seem to parallel the USB development path. Look for /dev/ttyACM0. Add your user to the group "dialout" IIRC. And have a lot of fun with Arduino and Linux. admin at lctn.org wrote: > I have a little kingdel box that has 5 actual, 9 pin serial ports. I am > working with arduino and need my active usb port to show up as a com > port, but it doesn't. > > ls /dev/tty* does not list any usb devices. Is there a way to make the > usb port a com port in this case? > > Ubuntu 18.04.3 LTS > > Raymond Norton > LCTN > 952.955.7766 > > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > tclug-list at mn-linux.org > http://mailman.mn-linux.org/mailman/listinfo/tclug-list >