Path: utzoo!attcan!uunet!husc6!bloom-beacon!mit-eddie!uw-beaver!uw-june!uw-entropy!dataio!pilchuck!ssc!fyl
From: fyl@ssc.UUCP (Phil Hughes)
Newsgroups: comp.unix.xenix
Subject: Re: modem answering at wrong speed
Summary: The answer and a poor solution
Keywords: modems 2400 1200 Xenix getty line speeds
Message-ID: <1373@ssc.UUCP>
Date: 25 Jul 88 17:00:21 GMT
References: <273@mjbtn.UUCP>
Organization: Slugland, USA
Lines: 41

In article <273@mjbtn.UUCP>, root@mjbtn.UUCP (Mark J. Bailey) writes:

> I have 1) Mitsuba 2400 Internal Hayes compat. modem and 2) Prometheus 2400P
> External Modem and my Tandy 4000 '386 system running SCO Xenix 2.2.2.  I have
> my modems set to answer at 2400 baud and then cycle to 1200 on a CR and then
> back to 2400.  They are supposed to reset to 2400 baud at logoff, aren't 
> they?  Well, what is happening is that on initial setup, they answer the 
> first calls just fine, and then when the user logs off, they answer the 
> next call properly at 2400 baud ... sometimes.  At other times, they seems
> to get "stuck" in a 1200 baud mode, and that is where they stay, regardless
> of getty sending at 2400 (supposedly), they still answer at 1200 baud.


Oh, yes, this one.  I have been living with it for so long I almost
forgot about it.  I blame this on what I would consider a design error
by Hayes in the control of the 2400 baud modem.  If the last command
you send the modem is at 1200 baud, it will stay at 1200 baud.

What happens is that after a hangup, XENIX might send additional data
to the modem.  For example, the end of a logout message after the
calling system has gone away.  It carrier detect has left, the modem
returns to command mode.  If the data is at 1200 baud, the modem
sets its baud rate to 1200.  The only way to get it back to 2400 is
to send a command at 2400.  Getty won't do this until carrier detect
returns and the modem will not connect at 2400 because it is "being
commanded" at 1200.

I never found a clean solution, but my dirty one almost works.
Every hour, cron starts a shell script that disables all the 2400
baud lines that are not in use, sends commands to the modems
(a few ATs or a reset are cool) to the modems and then enables them.
Ugly, but it almost works.

Hope this helps.

Phil Hughes, SSC, Inc. P.O. Box 55549, Seattle, WA 98155  (206)FOR-UNIX
    uw-beaver!tikal!ssc!fyl or uunet!pilchuck!ssc!fyl or attmail!ssc!fyl


-- 
Phil    uunet!pilchuck!ssc!fyl