> > question is is the root hub a requirement of the USB
> > controller design?
>
> Yes.
That is what I expected - so the maximum number of devices I can
plug into any given bus is really 126 since one device is always used
(doesn't have to be practical, just trying to pin down the limit).
> > Also, the 127 device limit is per controller right?
>
> Yes; however, the figure "127" is mostly symbolic, since it is not
> practical to have more than 10-20 *typical* devices
> connected. Your desk
> will look like a snake kingdom. You also are likely to run out of
> bandwidth, and maybe out of power as well. I can think of some very
> special USB hardware that fans out fast and wide, but that's not your
> normal keyboard, mouse or a printer...
"snake kingdom" - I like the image. I'm not planning on connecting
126 devices to any given bus, I just want to know the limits in theory.
> If you really want 256 serial devices connected through USB then
> probably you need to look at digiboard stuff. It will be cheaper and
> faster. Generally, what you are trying to do makes as much sense as
Though, if those serial devices are all going to be very low
bandwidth, say 9600 baud, and not necessarily used in parallel, then it
doesn't seem as limiting. Or is the CPU overhead still going to kill a
modern PC?
Thanks for your reply,
-poul
-------------------------------------------------------
This SF.net email is sponsored by: Get the new Palm Tungsten T
handheld. Power & Color in a compact size!
http://ads.sourceforge.net/cgi-bin/redirect.pl?palm0002en
_______________________________________________
[EMAIL PROTECTED]
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-users
