Re: Serial over CAT5

[Nigel Orr <nigel.orr@xxxxxxx>]

At 12:16 03/03/00 +0000, you wrote:
=20
>A multimeter, a multimeter, my kingdom for a multimeter...=20

Get yourself down to your local Maplin, and buy the cheapest meter they
have.  It costs about =A37, it's fairly naff, but will probably do
everythin=
g
you need a multimeter to do.  I've got a better all-singing/all-dancing one
that I usually use, but the little analogue one still wins occasionally!

Who needs 1% accuracy?  Maybe on one occasion in 1000?  Just about every
time I need a multimeter, it's either to see relative changes, or for a
quick 'working' or 'not working' answer... If it had a 1 digit display,
that would probably be enough for most occasions. =20
=20
>>I've got a couple of 9-pin serial to CAT5 adapters (unfortunately
sealed=
=20
>>units) and was wondering if anyone knew which wires are used from
the CAT5=
=20
>>end. I assume that it's not all of them so could I pass the audio
signal=
=20
>>from the line out on my sound card down it too? From my knowledge
of=20
>>serial comms were usually talking pins 2,3,7 (on a 25 way) what
about a=20
>>9-pin?

It depends what they implement- just Tx and Rx would only need 2 pairs, but
if it also passes 1 handshake in each direction, it might use all 4.
That's assuming it's all balanced, they could have bodged it onto 3 wires
if it doesn't need to work over long distances (more than 5-10m say).

>>One other thing... can I pass 5 volts down CAT5 safely... would
the=20
>>voltage at the other end of say 100m length of CAT 5 drop
significantly?

You can pass mV down cat-5 safely... if it's high impedance you will get
noise added though...  what are you wanting to use it for? =20

If it's the ibuttons again (piecing together a number of your postings!),
ISTR working out they would run off 150m odd of cat-5. =20

Contact Dallas and ask them if they have tested it on cat-5 if you don't
fancy ploughing through calculations or data sheets... they've been very
helpful in the past.  ibuttons are in a middling position on my
ever-growing todo list (ie lots of ideas and designs, no time to build them
yet!), so keep me posted on progress!

Nigel


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