USB Serial RS-232 Converter Question

[Nils Kassube]

Martin McCormick wrote:
> 	I have 2 USB RS-232 dongles that will be installed on a Ubuntu
> system, one per USB port. I determined which one was ttyUSB0 by
> trial and error, rebooted the system and it was still ttyUSB0.
> That's a very good thing, but my question is, is it likely to
> always boot up and assign the 2 dongles their tty numbers in the
> same order?

You can't rely on constant association of device and device name. The 
kernel gives the device name ttyUSB0 to the first device detected. If 
both devices are different models you can make your own udev rules which 
would create the wanted device name. See "man udev" and / or [1]. If both 
devices are the same type it isn't likely that you can distinguish them 
from the USB device information. With the command "sudo lsusb -v" you can 
check if there is a difference between the devices. If both devices look 
the same you would probably have to probe the device on the other end of 
the cable to find out which device is connected to which device name. You 
could then setup symbolic links to the correct device names and use the 
symbolic links instead of the device names directly.


Nils

[1] <http://reactivated.net/writing_udev_rules.html>