Modular jack serial lines on 3B2
andrew.d.hay
mvadh at cbnews.ATT.COM
Fri Apr 27 20:57:57 AEST 1990
In article <132 at bongo.UUCP> julian at bongo.UUCP (Julian Macassey) writes:
"In article <12 at lysator.liu.se>, aronsson at 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 at att.com +------------------------------------------------------+
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