Subject: Re: null modem cable question (i386)
To: None <netbsd-help@netbsd.org>
From: Andy Ball <andy.ball@earthlink.net>
List: netbsd-help
Date: 08/12/2004 08:36:41
Hello Juka,

   JS> Using a null modem cable, I can login on host B's
     > console from host A; however, I don't get a login on
     > host B's tty01.  Using a different null modem cable, I
     > can login on both the console and tty01...
     >
     > Both cables seem to be regular null modem cables; why
     > does login on tty01 only works with one of them, but
     > login on the console works with both of them? Any
     > hints?

I've seen a few     DB9 DB25                        DB25 DB9
different           ~~~ ~~~~                        ~~~~ ~~~
variations on the     3    2  TXD -----\/----- TXD  2    3
wiring of null-       2    3  RXD <----/\----> RXD  3    2
modem cables, this
is how I do mine.     7    4  RTS -----\/----- RTS  4    7
                       8    5  CTS <----/\----> CTS  5    8
Are you able to
check how your        4   20  DTR -----\/----- DTR  20   4
cables are wired?     6    6  DSR <-+--/\--+-> DSR  6    6
I'm guessing that     1    8  DCD <-'      `-> DCD  8    1
there may be a
subtle difference     5    7  SG  ------------  SG  7    5
between them.

Out of interest, what happens if you reverse the cable that
seems to work one way?

- Andy Ball