USB to Serial assignemts?

[Jeffrey Ross]

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