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From: hack@moxie.lonestar.org (Greg Hackney)
Newsgroups: comp.sys.att,unix-pc.general
Subject: Re: modem control
Message-ID: <3852@moxie.lonestar.org>
Date: 18 Dec 90 19:19:28 GMT
References: <1990Dec9.020043.273@cbnewsm.att.com> <1990Dec10.192820.12812@eci386.uucp> <1990Dec17.161947.9000@nmrdc1.nmrdc.nnmc.navy.mil> <37031@cup.portal.com>
Followup-To: comp.sys.att
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Lines: 38

LCDR Michael E. Dobson writes:
> on my 3B2/600G... I have to force DCD high which effectively
> means I can't do full modem control on bi-directional lines.

Thad P Floryan writes:
> I had this problem
> repost your query and I'll repost all the info again.

What is the book solution for modem control? That document was not in
the pile of release notes and manual upgrades for my 3B2 S5R3.2.2 OS.

I don't have any hardware manuals, but it appears that DCD is crossed
with DSR in the 8 conductor 3B2 AT&T RJ type Modem connectors.
To use 'cu', I had to force DCD high on my modem, that is until I
rewired the connector:

25 pin           8 conductor RJ
to modem         towards computer
---------        ----------------

   1 ---< Frm Grd >---- 1
 
   2 ---< RD/TD >------ 2

   3 ---< TD/RD >------ 3

   4 ---< RTS >-------- 8

   5 ---< CTS >-------- 5

   6 ---< DSR >-------- 7

   7 ---< SIG GRD >---- 4
 
   8 ---< DCD

   20 ---< DTR >------- 6