FC5 Canon LiDE 30 and libusbscanner

[James Wilkinson]

CroombeFP wrote:
> I have an LiDE20 (which is virtually the same machine) and it worked
> fine under FC3, FC4 and FC5. I think the clue is to have it connected to
> your system when you install FC5. I also found it helps to have it on a
> dedicated USB port rather than a port expander : quite why, I don't
> know.

Rick Stevens replied:
> Often it's a speed issue.  If you have a lot of stuff on a single USB
> port, the bandwidth gets shared between all those devices and can cause
> a problem.  I've run into this with USB cameras, too.

It can also be an (electrical) power issue: if I recall correctly, the
LiDE20 is bus powered, which means that it doesn't have a separate power
supply, but draws what it needs from the USB cable.

Some USB hubs are "powered" hubs: they have their own power supply, and
can supply plenty of juice to any peripherals. Others are unpowered.

I don't have much experience with USB hubs -- the cheap unpowered one I
have will power itself from the hub, and allow "downstream" devices to
draw power through the hub from the computer. But that obviously means
that I could have four power-hungry devices sucking power through a
cable and port (on the computer) that's only expecting to power one,
exceeding the USB specifications and the specifications of the
motherboard.

And a scanner is a relatively power-hungry device, even when it uses
LEDs as a light source -- it still has to emit quite a lot of light at
the same time as powering a motor.

James.

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E-mail address: james | Please do not put sandwiches in the disk drive.
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