Lorenzo J. Lucchini wrote:

> real-address-in-sig@flur.bltigibbet (Rowland McDonnell) wrote:
> > Lorenzo J. Lucchini wrote:

[snip]

> > > - and lastly, is it a possibility that my problems are instead caused
> > > by the fact that I'm using a cable to connect the reader to the USB
> > > port (something the Trust support site mentions for USB products in
> > > general, but I can't really connect the reader directly to the port on
> > > my desktop machine!)? I would think that the USB protocol had a way to
> > > not leave this kind of errors undetected...

> >
> > [snip]
> >
> > With computers, anything can potentially do anything to your data if it
> > gets a look-in. So I doubt that connecting the USB reader via a *cable*
> > would cause corruption, because a plain cable (not a long USB
> > `extension' cable with a 1-port bus-powered hub at the end) doesn't
> > listen to the data - I would expect it to either work, or not work.

>
> Well, it could be that too much interference is added to the signal
> turing the trip in the cable. With "it could be" I mean that, assuming
> USB is a protocol that pushes bandwidth a lot, and assuming it has no
> decent error detection (checksum) built-in, it could be possibly.
> I would hope this isn't the case of USB, though.


USB's hot-pluggable; that mean's it's *got* to have error detection.
And USB also uses differential signalling - which mean's it's inherently
low radiation and low pickup. But USB also carries power - hmm! Ah!
Yes.... My 5mx has often worked okay on low battery until I've asked it
to write to CF disc. If this CF card reader is bus powered, it might be
that it's not able to get enough power from the USB port to run it.
This *might* (but almost certainly isn't, or so I feel) mean that even
if the reader is plugged directly in a self-powered USB hub, it can't
get enough juice to run the electronics. But I can't see that because
USB is supposed to be good for 500mA at 5V per port, in the case of a
self-powered hub - and that's enough to run a floppy disc drive, for
gawd's sake (although I have heard of one floppy disc drive that could
only be run off *some* USB ports, because not all of them could provide
enough juice). But maybe a duff cable could result in voltage loss on
the power side of the USB wiring. Maybe. Doesn't sound very convincing
to me.

> > [snip]
> >
> > And... Well, you *can* plug the reader directly into your desktop
> > machine if you shift things around and don't mind getting grubby and
> > maybe unplugging a bunch of stuff you normally use. But I seriously
> > doubt that the problem lies with the wiring.

>
> I agree with you. Only, I can't think of another reason (except that
> the USB reader is broken).


Could be. Could it be broken driver software?

> I'll try the direct connection, assuming my computer doesn't complain
> *too* much about missing a keyboard... :-)


Good luck :-)

Rowland.

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