From owner-freebsd-hackers  Tue Jun 22 17:37:38 1999
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Date: Tue, 22 Jun 1999 19:37:24 -0500
From: Chris Csanady <ccsanady@scl.ameslab.gov>
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To: "Bill G." <billg@cyberwar.com>
Cc: freebsd-hackers@freebsd.org
Subject: Re: Serial Console Wierdness
References: <Pine.BSF.4.10.9906221322230.3019-100000@outland.cyberwar.com>
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"Bill G." wrote:
> 
> I got a serial console working on COM2, to which I have connected
> another FreeBSD box.  I connect with 'cu' fine, but I'm running into
> a couple of problems which I haven't been able to find and answer
> for.
> 
> o  When I connect, when the machine is first turned on, I get
>    disconnected twice during the boot up sequence (cu reports
>    Got hangup signal) -- looks like when the sio1 device is
>    probed, and also when getty runs.

This happens when the serial chip gets reset, and the DCD line
goes low for a moment.  For most local serial connections, you
really want to tie the DCD pin back to the DTR/DSR.  If you use
rj45 modular adapters, this is fairly easy.  I find the following
wiring to be rather convenient, as you have a single type of
adapter, which can used for just about anything.  If you use a
crossed ethernet cable, you will get a null cable, otherwise it
will be straight through.

     Signal   DB25     DB9      RJ45    Color

 ,--    DCD      8       1      NC
 |      TXD      2       3      1       Blue
 |      RXD      3       2      3       Black
 +--    DTR     20       4      NC
 |       SG      7       5      7       Brown
 `--    DSR      6       6      NC
        RTS      4       7      2       Orange
        CTS      5       8      6       Yellow

Hope this is of some use..

Chris


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