@gjacobse said in LINux: Comm port address changes:
As part of my use of *nix, I use it to access / control / program a few different radios. They use the FTDI chipset for serial communications. Generally I have no trouble, but every once in a while it seriously gripes my mood.
dmesg | grep tty
This will tell you the devices and the port to use. It's in my list of useful commands as I don't always need it, and I just haven't committed it to memory yet. But I have it -
So this week I have two devices connected, and I went in and found the one I needed to use with the radio I wanted to program.
TTY0 was connected to a radio that was off
TTY1 was connected to the radio I was working with.
Had some programming issues, and updated the software to the latest release using a different REPO, when I went back to program the radio - fails - repeatedly.
Reboots, updates, upgrades, re-installs later, I run dmesg | grep tty again and find that the port assignment has changed.
This is one of the frustrating things about *nix I seem to have, in that things don't stay where they where and where I expect them to be the next time I go to use them.
Is this normal for it to change, even though neither of the USB devices were not removed?
@scottalanmiller
Especially plugable devices (e.g. USB) tend to change names - if you plug them into other ports for example. But your example doesn't look like a USB serial adapter, they would most probably have a name like ttyusbN.
But like SAM said above, this is not only happening with plugable devices. Most modern distros will create udev rules whenever they detect new hardware (except for a few cases like USB devices). That's why you will (should) see a reproducable mapping every time the system starts.
Anyway. You could get more stable results using a udev custom rule for your tty problem.
First hit on Google: https://www.silabs.com/community/interface/knowledge-base.entry.html/2016/06/06/fixed_tty_deviceass-XzTf
