Path: utzoo!attcan!uunet!husc6!bloom-beacon!tut.cis.ohio-state.edu!mailrus!nrl-cmf!ames!pacbell!hoptoad!peora!rtmvax!bilver!bill
From: bill@bilver.UUCP (bill vermillion)
Newsgroups: comp.dcom.modems
Subject: Re: Packard Bell PB2400Plus
Keywords: modem trouble
Message-ID: <327@bilver.UUCP>
Date: 11 Dec 88 04:50:23 GMT
References: <297@esosun.UUCP> <2716@sultra.UUCP>
Reply-To: bill@bilver.UUCP (bill vermillion)
Distribution: na
Organization: W. J. Vermillion, Winter Park, FL
Lines: 39

>In article <297@esosun.UUCP>, keith@esosun.UUCP (Keith Pilotti) writes:
>> 
>> experiencing some glitches.  For example, it will connect at 2400 baud
>> one time, 1200 baud the next.  Of course, once it connects at 1200
>> baud it changes it's serial interface speed which then no longer talks
>> to the terminal port!  I wonder if it is this particular modem, or a
>> design flaw in the product.

Not sure if I am missing something here but, one of the "features" of the
v.22.bis (2400bps) modems, is that if the line gets too noisy to connect at
2400 it falls back to 1200.  (and depending on the modem mfr it may fall from
v.22.bis to v.22, or v.22.bix to 212a.  some permit setting of the fallback
protocols).

Now when it falls back from 2400 to 1200, you are still talking at 2400 and it
is all over, unless you change your interface speed.  We have much to thank
Hayes for, in the same way we have much to thank IBM for. :-) :-) :-) !!

At one time pin 12 would go high for 1200 and low for 300.  When Hayes brought
out their 2400 it now was pin 12 high for 2400 and pin low for 1200 or 300.
(Other mfrs - who work primarily in the commercial marketplace brought out
another pin to keep the 212a standard as data rate detect - previously
secondary carrier detect)

If you KNOW you are 2400 then look at pin 12, and when it goes low switch to
1200 bps on the interface.  (This hardware detect used to be the way to
determine whether incoming calls were 300 or 1200.  Now you have to get result
codes to determine the speeds.)

In other words - what you are experiencing is normal for a "Hayes" compatible
with standard comm software.  (Providing I interpreted your problem correctly
in that a 2400 call switches to 1200 and it is all over).

If the latter is the problem then a simple answer to your question is "yes it
is a design flaw - but not limited to that modem - just all modems that are
made to the "Hayes Standard".
-- 
Bill Vermillion - UUCP: {uiucuxc,hoptoad,petsd}!peora!rtmvax!bilver!bill
                      : bill@bilver.UUCP