I think on U/Linux the serial ports are named /dev/tty??? on my Xubuntu
12.04 they are /dev/ttySo on up. The USB ports are /dev/ttyUSB0 etc up
to the number of USB ports when something is plugged in like a sound
card or USB/Serial adapter.
Not sure how you can control them, other than making sure you plug in
the adapter to the same port each time. You can keep track by the
command line by typing in at your prompt "ls -l /dev/tty*" with out
quotes.

You can label them using Gparted or similar application or using Windows
using the file manager. My devices all come up with names that I have given
them or names that came with the device.

Not sure how Gparted labels USB or Com ports, I think Gparted only
labels disk partitions doesn't it?

I was looking at devices. Misread it. You are right. Trying
to catch up on a backlog too fast.

I'm afraid I didn't explain what I was referring to.

I have 3 USB devices that contain micro-controllers/processors. What I'm
trying to do is get them to communicate with my PC via USB. Sometime when I
plug one of the devices in it comes up as
/dev/ttyUSB0
Occasionally as
/dev/ttyUSB1
Occasionally, but rarely as
/dev/ttyUSB2

The comm program I using gtkterm has to be set/changed to match the port
designation Linux decides to call it even though I may be using the same
physical USB hole. In the days of RS232 the physical port set up as COM1
was always called COM1, or something similar, in the software. The software
did not name them dynamically. (I believe the comms could be ASSIGNED other
names but I never used or tried that.)

Anyway, is there a way to have a certain physical USB port be assigned a
specific ttyUSBx?

If not how can I get gtkterm find the port designation and change to it?

I have tried Minicom and Cutecom. Minicom did communicate after a few
minutes of setup but then for some reason, probably something I did,
decided not to work. A new install has not corrected this. Cutecom, it
seems like it is connected all the time. Characters typed are returned even
without the device on the other end Tx and Rx pins not strapped for
loop-back and echo is supposedly turned off.

I'm also open for trying another comm program.

For flash cards and USB sticks, you can label them or rename them.

Unlike the com ports of the past, USB devices are "hot pluggable".
Because of this they are assigned names when the device is found. If
the USB device is plugged in on power up it will maintain its location.
This is not important because each manufacturer has assigned numbers for
the devices they make. The handlers know the numbers and find and attach
the hooks needed to use the device according to name.

I'm also open for trying another comm program.

Reply : picocom in repos