[sane-devel] How many scanners on an ieee1394 bus

Jonathan Buzzard jonathan@buzzard.org.uk
Sun, 12 Jan 2003 10:21:17 +0000

andras@users.sourceforge.net said:
> As many as these busses take, in principle. There might be a limit on
> IEEE1394 simply because you run out of sg devices after a while, but
> I'm not sure what the limit is. As a matter of fact, I'm not even sure
> how many devices you can have on an IEEE1394 or USB2. 

For USB 1 or 2 it is 127 devices on the bus and you have to have a master
device controlling the show. Usually the computer and you can only have
one such device. So you cannot easily plug the same USB device into
two computers at once.

For IEEE1394 (or FireWire/iLink) it is 64 devices on a bus, and no
requirement for a master device, as all devices can be a master. So you
can simply sling a Firewire cable between two machines and they can talk
to one another over it, or you can connect the same device (scanner,
hard disk etc.) to two machines at one. These are things you cannot do
with USB. Rounding off the maximum number of scanners on a single IEEE1394
bus would in theory be 63.

However I doubt you get get anywhere near either of these maximum figures
before things fall over.


Jonathan A. Buzzard                 Email: jonathan@buzzard.org.uk
Northumberland, United Kingdom.       Tel: +44(0)1661-832195