From owner-freebsd-hackers  Thu Jan 10 20: 9:34 2002
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Date: Thu, 10 Jan 2002 20:09:20 -0800
From: Terry Lambert <tlambert2@mindspring.com>
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To: Leo Bicknell <bicknell@ufp.org>
Cc: Lyndon Nerenberg <lyndon@atg.aciworldwide.com>,
	Alfred Perlstein <bright@mu.org>, John Baldwin <jhb@FreeBSD.ORG>,
	freebsd-hackers@FreeBSD.ORG
Subject: Re: serial console + boot blip
References: <20020110160848.T7984@elvis.mu.org> <200201110049.g0B0nu2I044666@atg.aciworldwide.com> <20020111005220.GA19912@ussenterprise.ufp.org>
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Leo Bicknell wrote:
> > Or just wire CD to DTR on the offending device.
> 
> For reference, I'm 96% sure the problem in this case is the termainal
> server paying attention to DTR, I believe the way it's configured
> now it ignores CD.

Uh, DTR is the termial equivalent of a modem's DSR + DCD.

Your serial port is either DTE or DCE.  Off the shelf PC
hardware is wired as DTE -- terminals.

Your terminal server is probably wired as DCE, unless you
actually need a null-modem cable to hook a PC to it?

If you want your terminal server to not know when a client
machine goes away, you need to make it ignore DTR.

The easiest way to do this in hardware (assuming you can't
just set the terminal server up to do it in software) is to
wire CTS and RTS together with DTR on the server side, and
CTS to RTS, DCD and DSR on the terminal side, with only 2,3,
and 7 going through, with all other wires unused in the cable
and hooked to pin 1 on one side only to avoid ground loops.

Probably it would be best if you changed your terminal
server settings...

-- Terry

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