You can also have a look to this module:
http://www.ftdichip.
com/Products/EvaluationKits/UM245R.htm
PaoloC
----Messaggio
originale----
Da: xxxxx@probo.com
Data: 10-mag-2006 1.12 AM
A: “Windows
System Software Devs Interest List”
Ogg: Re:
[ntdev] Parallel port legacy application issue
Bruno van Dooren wrote:
>I have been asked by a colleague to help him out with a parallel
port
>problem.
>the problem is that they have an application that
controls an external
>device via the parallel port.
>communication is
implemented by reading and writing bytes on the parallel
>port via
port io functions on a specific port.
>
>now they want to be able to
run the program on a pc that has no real io
>port, so they want to use
a USB to parallel convertor.
>the old app doesn’t work anymore, so he
asked me what I could do about it.
>
>since we have the app sources, I
was thinking about simply opening a handle
>to the virtual comm port,
and then reading and writing on the handle, though
>I can forsee some
timing problems, and I don’t know if the lines retain the
>value of
the last byte that was sent (it is a requirement).
>
>my question: does
anyone perhaps have an alternative approach, or some tips?
>I have
searched around, but could not find any useful information yet.
>most
information is about port io, which is exactly what I cannot use in
>this case.
>
The USB-to-parallel connectors USB Print Class spec;
they are designed
for shipping bulk data to real printers. They aren’t
designed for
low-level tweak-the-wires access. There’s no guarantee
that reads and
writes actually map to reads and writes to the parallel
pins in any
sensible way. Writes probably works as you expect, but
reading is
problematic.
Is this a laptop? There are some good PCMCIA
parallel port cards. You
may also be able to get a PCI parallel port
card.
Alternatively, there are a couple of companies who sell very
simple USB
devices with terminal blocks on the other end, designed
specifically for
your kind of tweaking. Here’s one:
http://www.
accesio.com/go.cgi?p=../digital/usb-dio-32.html
–
Tim Roberts,
xxxxx@probo.com
Providenza & Boekelheide, Inc.
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