Date: Tue, 22 Jun 1999 19:37:24 -0500 From: Chris Csanady <ccsanady@scl.ameslab.gov> To: "Bill G." <billg@cyberwar.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Serial Console Wierdness Message-ID: <37702C44.993BFADB@scl.ameslab.gov> 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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