USB to Serial assignemts?
Jeffrey Ross
jeff at bubble.org
Sun Dec 10 02:38:50 UTC 2006
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
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