[sane-devel] USB to parallel port converters

Neil Youngman ny at youngman.org.uk
Sat Dec 8 18:27:51 UTC 2007

On Saturday 08 December 2007 17:39, Steve Underwood wrote:
> Neil Youngman wrote:
> > I would be surprised if the adapter didn't support bidirectional ECP/EPP
> > modes, but I could always be wrong. It was advertised as a printer
> > adapter. There may be some modes required for scanners that it doesn't
> > support, however I suspect that the problem is more likely to be SANE
> > assuming that parallel port devices are only found on parallel ports and
> > not on USB. Does anyone know if this is the case?
> >
> > Neil
> Then be prepared to be surprised. A USB serial gadget is a close
> emulation of a traditional serial port. A USB parallel gadget is not
> even vaguely similar to a traditional parallel port. The huge latency of
> USB means it would be impractical for it to work in the same way. This
> is a huge pain for a wide range of industrial gadgets, embedded
> development tools, and other gizmos which only work with a PC's parallel
> port. Even if you try written a custom for the USB gadget, the latency
> makes it useless for almost anything.

People seem to be able to able to get scanners working on USB, so I guess 
you're saying that the USB to parallel port conversion can't be made to work 
adequately for bidirectional transfers?


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