USB to Serial assignemts?
Mikkel L. Ellertson
mikkel at infinity-ltd.com
Sun Dec 10 02:50:04 UTC 2006
Jeffrey Ross wrote:
>
>
> Mikkel L. Ellertson wrote:
>> Jeffrey Ross wrote:
>>> How does Fedora assign which USB to serial adapter is assigned
>>> /dev/ttyUSB0, /dev/ttyUSB1 etc through a reboot?
>>>
>>> I basically want to make sure that one specific USB adapter remains at
>>> one location throughout a reload and unfortunately the on board serial
>>> port doesn't work (hardware problem)
>>>
>>> Thanks..Jeff
>>>
>> I believe it assigns them in the order it finds them when scanning
>> the bus. Changing where the adapter is plugged in, ro plugging in
>> another serial device can change that. You may want to consider
>> creating a udev rule that creates a symlink to that serial adapter
>> with a meaningful name. I do this with the serial adapter for my
>> GPS. (Actually, this is my old rule. I am working on having it tell
>> gpsd that it was added/removed, and supporting more then one
>> device.) If you have more then one device with the same vender and
>> product ID, you can also test the serial number.
>>
>> KERNEL=="ttyUSB*", SYSFS{idVendor}=="067b",
>> SYSFS{idProduct}=="aaa0", SYMLINK+="gps"
>>
>> Mikkel
> Since I have two of these USB to serial adapters made by the same
> manufacture
> I guess the serial number is going to be the way to go, and I like the
> symlink
> idea, makes sense and is easy enough to implement in my scripts.
>
> The device according to "lsusb -v" shows the following (among a lot of
> other stuff):
>
> idVendor 0x050d Belkin Components
> idProduct 0x0109 F5U109/F5U409 PDA Adapter
> bcdDevice 1.02
> iManufacturer 1 Belkin USB PDA Adapter
> iProduct 2
> iSerial 3 799020
>
>
> If I understand correctly I would create a file in /etc/udev/rules.d say
> /etc/udev/rules.d/serialusb an put the following lines:
>
> KERNEL=="ttyUSB*", SYSFS{idSerial}=="799020",
> SYSFS{idProduct}=="0109", SYMLINK+="serial"
>
> The next time the device was inserted into the USB port udev would create
> the mapping so that /dev/serial was always this adapter.
>
> Did I get it right?
>
> Thanks!
>
> Jeff
>
It looks right. I would put it a local rules file - something like:
/etc/udev/rules.d/10-local.rules
Mikkel
--
Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!
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