Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ames!amdahl!pacbell!att!cbnews!mvadh
From: mvadh@cbnews.ATT.COM (andrew.d.hay)
Newsgroups: comp.sys.att
Subject: Re: Modular jack serial lines on 3B2
Message-ID: <16066@cbnews.ATT.COM>
Date: 27 Apr 90 10:57:57 GMT
References: <132@bongo.UUCP>
Reply-To: mvadh@cbnews.ATT.COM (andrew.d.hay,54242,wi,1d007,508 374 5484)
Distribution: comp
Organization: AT&T Bell Laboratories
Lines: 32

In article <132@bongo.UUCP> julian@bongo.UUCP (Julian Macassey) writes:
"In article <12@lysator.liu.se>, aronsson@lysator.liu.se (Lars Aronsson) writes:
"> 
"> I was planning on going modular for my RS232 serial lines and was
"> looking for standard, but there seems to be none.
[]
"	A gotcha. Some line cords will rotate from one plug end to the other. 
"Pin 1 will go to 8 and 7 to 2 etc.

there is a sort of de facto standard for the rj45 (8-pin mod)
connector, but for some odd reason at&t reversed it for the sockets on
the 3b2...  if you want to connect a 3b2 to *anything*, you need a
'half-twist' cable.  rs232 to rj45 adaptors generally (always, in my
experience) follow the standard; equipment such as the at&t data
switch ('datakit') also do.
why the arrangement of signals is as it is instead of something
rational like
	gnd
	dsr
	rts
	txd
	rxd
	cts
	dtr
	gnd
i don't know.  they could have made the question of null modems moot.

-- 
Andrew Hay		+------------------------------------------------------+
Ragged Individualist	|	 But I thought we were *ALL* iconoclasts!      |
AT&T-BL Ward Hill MA	|		I was just trying to fit in!!!	       |
a.d.hay@att.com		+------------------------------------------------------+