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Re: Serial Connection





----- Original Message -----
Sent: 3/26/2011 10:52:23 PM
Subject: Serial Connection

On Mon, 21 Mar 2011 at 17:45:17 +0100, MAROUNI Abbass wrote:
>
> I have two servers with Debian Lenny installed.
>
> The two servers have a serial cable connected form Stty0 on Server0
> to Stty1 on Server1. I can use minicom to log into Server0, but when
> I try to login to Server1 from Server0 using minicom I get some garbage
> and I can't type anything with the keyboard.
>
> Any Ideas??

I haven't tried this, but one thing you want to make sure of is that
you use a "cross-over" cable. The serial ports on PCs have what's known
as a DTE interface (Data Terminal Equipment). The serial ports on
modems have what's known as a DCE interface (Data Communications
Equipment). A standard serial cable is designed to connect a DTE
interface to a DCE interface (i.e. a computer to a modem).
What you are trying to do is connect two DTE interfaces together.
For that you need to use a special serial cable called a "cross-over"
cable which is specifically designed to connect a DTE interface to
another DTE interface. If you try to use a regular serial cable,
one designed to connect a DTE interface to a DCE interface, it won't work.

An alternative to using a cross-over cable is to use a device called
a "null modem" on one end of your serial cable. A null modem attached
to a standard serial cable effectively converts it into a cross-over
cable.

Connecting a serial printer to a computer also requires a cross-over
cable or a standard cable plus a null modem, since both devices have
a DTE interface.

You also might have to use two cables and two serial ports. One serial
port looks like a modem, with you as the terminal. minicom
allocates it. The other serial port looks like a serial console,
with you as the host. getty allocates it. The other server sees
a similar pattern.

--
.''`. Stephen Powell
: :' :
`. `'`
`-
There's usually more than crossing Transmit Data and Receive Data.  There are at least two control signals that are applicable.  Usually one "borrows" what is known as a break-out box to determine which signals each side of the interface are active.  There are lots of good googles for RS-232 that will help.

Larry


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