Subject: Re: Formal getty replacement yet?
To: <>
From: Bakul Shah <>
List: current-users
Date: 12/21/1994 04:01:24
I have nothing new to say re: cua/tty versus a user level
solution but this sentence caught my eye.

> If *the* answer is to build a correct cable, then it's the only answer
> that's practical.

Actually, building a ``correct'' DB25<->RJ45 or db9<->rj45
connector allows you to connect pretty much any RS232 device
to any other RS232 device.  One can get away with this
solution in more than 90% of cases (in my experience.  YMMV
etc.)   Whether your device is DCE or DTE and has male or
female port, the trick is to wire the db25-rj45 so that on
the rj45 side you see something like the following

	1 cts
	2 dsr/dcd
	3 rcv
	4 gnd
	5 gnd
	6 xmt
	7 dtr
	8 rts

Given this arrangement you can use a 4/6/8 conductor cable
with a 4/6/8 pin jack with the usual half twist in the
cable.  The half twist ensures that your rcv connects to
your peer's xmt and so on.  A 4 conductor cable is enough
for a local device if you don't need to worry about dsr/dtr
and h/w flow control.

Once you figure this out for a particular device (or
computer), permanently attach the connector to that device
or atleast label the connector so that you know which device
it is for (or else chaos ensues as I ruefully found out).
At one point I had all my computers, modems, printer, X10
CP290 controller, EPROM/PAL programmer, miniboard etc. wired
this way, which allowed me to connect anything to anything
else without having to worry about finding a proper cable.
Granted that a few signals (such as Ring Indicator) are lost
but I've not needed them as much.

Credit for this idea and many thanks for bringing some order
into the chaotic world of RS232 goes to Dave Yost.

Apologies once again for going off on a tangent.


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