Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rochester!ciaraldi
From: ciaraldi@rochester.ARPA (Mike Ciaraldi)
Newsgroups: comp.dcom.modems
Subject: Dialin Recommendations?
Message-ID: <25678@rochester.ARPA>
Date: Sun, 8-Mar-87 21:08:13 EST
Article-I.D.: rocheste.25678
Posted: Sun Mar  8 21:08:13 1987
Date-Received: Mon, 9-Mar-87 18:57:13 EST
Reply-To: ciaraldi@rochester.UUCP (Mike Ciaraldi)
Distribution: world
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 38

[I ain't afraid of no line-eater]


This question seems to come up every few months, 
so now it's my turn.

Some friends with a MicroVax running VMS need modems foor their
incoming serial lines.  They want 300/1200/2400 b.p.s. capability
and the ability to occasionally dial out.
If it matters, the modems would be connected to an Emulex
multiplexer, which emulates a DH-11.

They tried some Codex 2233 with bad results.  First, they had
to fiddle with the settings for quite a while to get the combination
they needed.  Once they were set up, the modems were very
inconsistent.  You culd dial in to the same modem 10 times in
a row, and get a random mix of respones.  One time it might work.
The next time you would get a carrier from the Codex, but as soon as
the calling modem sent its carrier the Codex would hang up.
Another time the Codex would send its carrier, the sendingmodem
would too, the  line would  stay connected indefinitley, but the
Codex would never send "Carrier Detect" to the Vax.
Also, once the modem stepped down to 300 baud it would
not try to receive the next call at 2400 again; it would
stay at 300 until manually reset.

Then they tried some Hayes-compatible 2400-bad modems,
but those had to be initiaized through software to make them
auto-answer, not send messages, etc.  This stuff has to be done,
but cant be done with switches (the Hayes 2400 doesn't have
switches like the 300 and 1200).  So, that would have to be sent out
the port when the system is powered up.

We have several others coming in for evaluation, but would be interested
in others' experiences.

Mike Ciaraldi
seismo!rochester!ciaraldi