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From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.dcom.modems
Subject: Re: Invisible modems ?
Keywords: Modem RS232 UNIX Sun
Message-ID: <1990Aug30.133921.980@chinet.chi.il.us>
Date: 30 Aug 90 13:39:21 GMT
References: <1909@jura.tcom.stc.co.uk>
Organization: Chinet - Chicago Public Access UNIX
Lines: 30

In article <1909@jura.tcom.stc.co.uk> rajesh@tcom.stc.co.uk (Rajesh Kirpalani) writes:

>      On the Sun I am using the command :-
>
>           ( stty 2400 ; echo ATD number ) > /dev/ttya
>
>       The above does not work. The modem does not execute the Hayes command. 

Assuming that the modem is set to hold the DCD line up even when there
is no connection (otherwise you won't be able to send anything out
the port from a shell script), the problem is that you are sending
characters after the dialing command before the connection is established,
probably as a result of the outbound carriage return being translated
into CR/LF.  This can be avoided with appropriate stty options.  Also,
unless the modem is configured to ignore the DTR lead, it will drop
the connection as soon as the command completes - you will need to something
like "sleep several_seconds &" in the script to hold the port open while
the other program starts up.

>    Does any one know what the problem is ? Any solutions/ideas/pointers 
>    would be most welcome.

I'd recommend writing the dialer in 'C' where you have more control over
the low level details (i.e. you can handle the carrier detect lead properly
and detect whether you actually have a connection or not).  Or you
might try using kermit to dial, then run the application as a shell
escape.

Les Mikesell
  les@chinet.chi.il.us