device identification

Omer Ihsan omrihsan at gmail.com
Tue Mar 23 15:49:08 CET 2010


On Mar 23, 9:22 am, Tim Roberts <t... at probo.com> wrote:
> Omer Ihsan <omrih... at gmail.com> wrote:
>
> >i have installed pyusb now and run the sample usbenum.py....i have 3
> >usb ports on my PC but the results show 6 outputs to
> >dev.filename..they are numbers like 001 or 005 etc.... and they
> >changed when i plugged in devices...(i am no good with the usb
> >standards)....i just want to identify each device/port... what
> >parameter in the example would help me....
>
> You can't identify the ports.[1]  What good would it do you?  The ports on
> your PC are not numbered.
>
> You certainly CAN identify the devices, by their VID and PID (or idVendor
> and idProduct).  You identify by function, not by location.  When you plug
> in a USB drive, you don't want to worry about where it's plugged in.
> ===
> [1]: OK, technically, it is not impossible to identify the port numbers,
> but it is quite tedious.  You need to chase through the sysfs expansion of
> your buses hub/port tree and find a match for your device.  It's not worth
> the trouble.
> --
> Tim Roberts, t... at probo.com
> Providenza & Boekelheide, Inc.

VID and PID is fair enough. now what i want is that i have a threaded
code that threads two functions to run at the same time. i want each
function to run seperate devices. the problem is if it doesnt identify
the attached devices it might run the code on a single device which
isnt what is required.
how will i be able to run a code on a device of my choice???....you
can leave away the threading part for now.



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