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From: eravin@dasys1.UUCP (Ed Ravin)
Newsgroups: comp.sys.att,comp.unix.questions
Subject: Re: UUCP dialout, uugetty fighting...
Message-ID: <1187@dasys1.UUCP>
Date: Thu, 3-Sep-87 11:15:27 EDT
Article-I.D.: dasys1.1187
Posted: Thu Sep  3 11:15:27 1987
Date-Received: Sat, 5-Sep-87 17:49:32 EDT
References: <2896@psuvax1.psu.edu> <1463@chinet.UUCP> <18171@amdcad.AMD.COM>
Reply-To: eravin@dasys1.UUCP (Ed Ravin)
Organization: Ministry of Information Retrieval, DZ-103
Lines: 80
Summary: set hayes clone to dumb for dialin, smart for dialout
Xref: mnetor comp.sys.att:1140 comp.unix.questions:3880

I see people are trying to set up 2400 baud modems with uugetty and the
like.  Here's a quick summary of my experiences with a few Unix systems
and a few modems:

First things first:  when you get your Hayes-clone modem from the
factory, it is configured so a PC user will be able to use it with the
least amount of pain.  This means that the modem is set to echo input
when in command mode (so the PC user can see what they're typing), to
give you messages like OK or RING when the phone rings (so the PC user
will know what is happening), and to ignore DTR as an enable command
(in case the PC cable isn't wired properly).

All three of these features MUST BE DISABLED if a Hayes modem is to
work properly as a DIAL-IN modem.  On the original Hayes SmartModem
1200, you must adjust the DIP switches behind the front panel.  On
the 2400 baud modems, you must turn off these parameters via commands
over the serial port and then send the command to "burn in" the
configuration settings (save them in the non-volatile RAM of the modem
so that they will be the default power-up parameters).

(Why must these features be disabled?  You'll get the "getty-war" if
you leave local echo on, as the modem echoes the getty message and the
getty tries to log itself in.  The "RING" message when the phone rings
will also fool getty and this will interfere with the login
procedure.  Telling the modem to be enabled/disabled by DTR is
optional, but hangup commands (stty 0) won't work without it, and the
connection is much less reliable if the computer is unable to hang up
and reset it.)

The above covers setting up a modem for INCOMING CALLS only.  If you
want to set up a Hayes-beastie for OUTGOING CALLS ONLY, this is also
possible.  The only thing you really have to do is to turn off
auto-answer in the modem.  This is done by the DIP switch on the
original Hayes 1200 modems, or by ATA0 and the burn-in command on
the smarter, faster modems.  Now you can set up your "chat script" or
"acucap" or "modemcap" or whatever dial-out language your system uses.
You might want to disable the "+++" feature that lets the modem be
commanded out of on-line mode and into command mode, to prevent
accidents.  Other than that, there should be no problems.  You should
leave the status messages like "OK" and "NO CARRIER" and (especially)
"CONNECT" ENABLED so that your chat script can tell if the modem is
alive and if the phone call succeeded.

If you've been patient enough to read this far, then you're probably
also patient enough to be able to set up a Hayes-critter for INCOMING
AND OUTGOING calls.

First problem: support for bidirectional modems in many Unix systems
is non-existent.  You must either have a version of "uugetty" that
understands the lock files used by UUCP and can create them when a
person logs in on the modem, or a version of "uucp" and "cu" that is
smart enough to disable the getty on a port that it wishes to dial out
on.  The Unix PC uses the latter method, and the 3b2/3b5 Unix comes
with the former.

For a Hayes-thingie modem, use the "uugetty -r -t 60" options.  The
"-r" tells uugetty not to consider the port open until a character is
received.  This is because a port is usually considered open when DCD
is sensed.  But for an outgoing modem, you must configure the modem so
that DCD is always on, otherwise you wouldn't be able to connect to it
to tell it to dial.  So uugetty with the "-r" option will wait until
someone types something (and it can't be the modem typing in the word
"RING"!) before it will create the lock file, effectively locking out
uucp or cu from using the port.

Second problem: we can't dial out effectively if the status messages
like "CONNECT" are turned off.  We had to turn them off so that we
wouldn't get fouled up by the "RING" message when the modem was used
for incoming calls, but now we need them back.

My solution was to use the "DTR reset causes modem to switch to
power-up default" option of my Hayes 2400 clone.  I programmed the
modem to be an INCOMING modem, with status messages turned off.  Then
I created a chat script that would turn the status messages back on
before the phone number was dialed when an outgoing call was made.  If
the call connected, the dialer would receive the "CONNECT" message
from the modem.  When the call was hung up, the modem would reset to
its power-up defaults, which would turn the status messages back off
again.
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