Re: Parallel Cables

[Nigel Orr <Nigel.Orr@xxxxxxx>]

At 18:09 31/07/00 +0100, you wrote:
>AIUI, he wants to drive an LCD at the remote end, from a PC parallel
>port, so he's not strictly sending parallel data, just using a couple
of
>the conductors.

Are you sure?  All the parallel port LCDs I've used need at least 8 data
lines, ground and one handshake line.  I know there are ones now with
serial interfaces built in, but are they then sold for connection to
parallel ports with software to make the parallel port pretend to be a
serial port?  Sounds like the long way round...

I'd agree with the 30ft limitation, but I'm not sure what the official
figure is, the practical maximum does depend on how fast you are running
it.  Longer distances will suffer increasing crosstalk and noise.  Beyond
that, you really need to convert it to something like RS-485 with an
intelligent adaptor at each end.  I produced one of those here last year,
to control a DSP card in an underwater housing down 100m of a single pair
of cable, which only had a parallel interface.  It might be easier to just
buy a serial LCD and put RS-232 to RS-485 converters on the data lines if
it doesn't work well enough.

Nigel


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