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Path: utzoo!utgpu!water!watmath!onfcanim!dave
From: dave@onfcanim.UUCP
Newsgroups: comp.dcom.modems
Subject: Re: Can't get out of command mode
Message-ID: <15500@onfcanim.UUCP>
Date: Sun, 6-Dec-87 03:01:56 EST
Article-I.D.: onfcanim.15500
Posted: Sun Dec  6 03:01:56 1987
Date-Received: Fri, 11-Dec-87 00:48:23 EST
References: <15491@onfcanim.UUCP>
Reply-To: dave@onfcanim.UUCP (Dave Martindale)
Organization: National Film Board / Office national du film, Montreal
Lines: 28

Michael T. Sullivan (richp1!mike) provided the solution.  In
retrospect, it's so obvious I'm embarassed....

I had complained that most of the time I used the "escape sequence" to
put my local modem into command mode, my connection to UNIX was
apparently hung when I attempted to go online again.  What happens is
that as I type the three plus signs in rapid succession, the local
modem sends them to UNIX where they are echoed back to my terminal.
Just as my local modem sees its "escape sequence" and goes into command
mode, if the UNIX-end modem is a Hayes-compatible it also goes into
command mode and ignores further characters from the phone line.

Since the UNIX-end modem is not listening to the line, and UNIX is not
likely to send the string "ATO\r" on its own, the connection is now
hung until I hang up the phone.  The fix is simple - turn off the
escape sequence on the modems at the UNIX end (s2=255 on the Hayes,
s55=3 on the Telebit).

These modems are used by uucico in originate mode as well as being
dialin lines, but uucp never really needs to talk to the modem once it
has established a connection.  (The stock Hayes dialer routines use the
escape sequence to tell the modem to reset at the end of a call, but
they can easily be changed to drop DTR to hang up the phone first,
putting the modem back into command mode that way.)

Anyone that wants to use the modems for tip AND wants to use the escape
sequence will have to change the appropriate s-register before
dialing.  Too bad.