Re: RS-232 to RJ45 adapters?

Jay Hennigan (jay@west.net)
Sat, 8 Jun 1996 06:52:16 -0700 (PDT)

On Sat, 8 Jun 1996, Dave Carmean wrote:
> Roger's Systems Specialist
> 21021-504 Soledad Cyn. Rd.
> Santa Clarita, CA 91351 USA
> (800)-366-0579
>
>
> TE-5M8 DB25 male to 8 cond RJ45 1.50 ea
> <http://www.rogerssystems.com/Catalog/RSCAT12.GIF>

And they're only $1.20 each if you buy 100 at a time.

> Now, about pinouts....take a look at this page on the "Yost" method....
>
> <URL:http://www-scf.usc.edu/~khendric/info/yost.html>
>
> My only beef is that it leaves out DSR in favor of having both center
> pins be signal ground. But they've included DTR....this doesn't
> make sense to me, and it also didn't work. I ditched one of the redundant
> ground pins and put DTR there instead.

Anoother problem with this method is that the TD and RD lines, when used
with twisted-pair telephone cable, are twisted with each other. This can
cause near-end crosstalk problems. Better to have each one paired with a
pin that doesn't change state during an established session. For short
runs or with flat cable this is a non-issue.

Also, the Yost method requires that you solder or otherwise splice the
two ground wires to a single pin on the DB 25, a bit of a hassle.

We use:

DB-25 Signal Color Mod Jack
2 TD Red 4
3 RD Black 3
4 RTS Orange 2
5 CTS Blue 1
6 DSR Brown 7
7 SG Green 5
8 DCD White 8
20 DTR yellow 6

You'll still need to make up null hoods this way for those applications
that need them, but it's easier to find a hood with a big "NULL" written
on it than to closely examine a bunch of cords to see how the plugs are
pinned.

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