[gentoo-user] udev and multiple usb-serial devices

[gentoo-user] udev and multiple usb-serial devices

[Graham Murray]

Is there any logic to the order in which usb-serial devices are
enumerated when a system starts?

When using multiple usb-serial devices, the program(s) have to know to
which port each particular external device is connected. When
initially connecting, the first to be plugged in will be /dev/ttyUSB0
and so on. Having connected them all, looking at the output of
udevinfo, I can see the bus address to which each port is connected
and can create udev rules to create aliases to 'fixed' names which the
programs can reference. However when the system was restarted, the
mappings were wrong and the bus addresses for some of the ports were
swapped. I expected the /dev/ttyUSBx names to change, that is why I
tried mapping to the bus ID (eg 1-4.1:1.0).

Is there any way to write udev rules which will map the usb-serial
device connected to a particular socket on either the PC or a hub to a
known name? So that if the usb connector is removed and replaced (in
the same socket) or the system is rebooted that programs will be able
to open the correct device connected to each usb serial adaptor?
-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] udev and multiple usb-serial devices

[Neil Bothwick]

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On Thu, 17 Aug 2006 13:58:11 +0100, Graham Murray wrote:

> Is there any way to write udev rules which will map the usb-serial
> device connected to a particular socket on either the PC or a hub to a
> known name? So that if the usb connector is removed and replaced (in
> the same socket) or the system is rebooted that programs will be able
> to open the correct device connected to each usb serial adaptor?

Use a pattern match for ID, e.g. ID=="2-*". the first number of the ID
refers to the physical port used. Alternatively, if the devices are
different, match on SYSFS{product}, SYSFS{manufacturer} or even DRIVER.


-- 
Neil Bothwick

Life is a sexually transmitted disease and the mortality rate is 100%.

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