[comp.dcom.modems] Problems between T2500 and Hayes V series modems?

gs26@prism.gatech.EDU (Glenn R. Stone) (02/22/91)

In <786@dynasys.UUCP> jessea@dynasys.UUCP (Jesse W. Asher) writes:

>Has anyone had problems getting a T2500 and a Hayes V series modem
>connected?  I'm having a strange problem - the modems connect but
>connect at 300 or 2400 baud and sometimes the T2500 doesn't get a 
>CONNECT message.  Anyone have any ideas on what could be causing this?

Yep.  Incompatible protocols.  The Hayes V-series modems do a fast-turnaround
half-duplex ping-pong weirdness (sorry, Toby) that won't talk to anything
else but another Hayes V at 9600.... so the T2500 negotiates the fastest
speed it can that has a compatible protocol, namely V.22bis at 2400 baud.

I think this one is a candidate for an FAQ....  I also think that anyone
with a V-series that's serious about talking to the world should upgrade
to a T-1600, an Ultra 96, or something else that's truly V.32.... 
(this assumes interactive use and decent lines.... no comment on 
what to use if either or both of these assumptions isn't valid :)

-- Glenn R. Stone
gs26@prism.gatech.edu

gandrews@netcom.COM (Greg Andrews) (02/22/91)

In article <786@dynasys.UUCP> jessea@dynasys.UUCP (Jesse W. Asher) writes:
>Has anyone had problems getting a T2500 and a Hayes V series modem
>connected?  I'm having a strange problem - the modems connect but
>connect at 300 or 2400 baud and sometimes the T2500 doesn't get a 
>CONNECT message.  Anyone have any ideas on what could be causing this?

I've seen this several times.  It only happens when the T2500 calls the
V-9600, and the V-9600 is *not* an Ultra 96.  If the V-9600 calls the
T2500, things are fine.  Setting S50=3 (limit the modem to V.22bis and
slower modulations) in the T2500 takes care of the problem and the modems 
connect at 2400 without a hitch.

My best guess is that it's due to a slight confusion between the modems 
when they try to handshake.  The T2500 thinks a V.32 modem answered, and 
the V-9600 seems to think that another V-9600 called.  The two modems try
to proceed with different handshake procedures, and encounter trouble.
By the time they recover, they can't get resynchronized, or they only
get a 300 bps link.  Maybe someone else (Toby?) can say whether this is
what's actually happening, or if it's something else...

Telling the T2500 to act like a plain old V.22bis modem seems to eliminate
the problem.

-- 
.-------------------------------------------.
| Greg Andrews      |   gandrews@netcom.COM |
`-------------------------------------------'

kevin@msa3b.UUCP (Kevin P. Kleinfelter) (02/22/91)

jessea@dynasys.UUCP (Jesse W. Asher) writes:

>Has anyone had problems getting a T2500 and a Hayes V series modem
>connected?  I'm having a strange problem - the modems connect but
>connect at 300 or 2400 baud and sometimes the T2500 doesn't get a 
>CONNECT message.  Anyone have any ideas on what could be causing this?

2400 is the best you'll get here.  The only protocols that the Telebit
T2500 and the Hayes 9600 V-series have in common are 300, 1200, and 2400.
-- 
Kevin Kleinfelter @ Dun and Bradstreet Software, Inc (404) 239-2347
{emory,gatech}!nanovx!msa3b!kevin

Look closely at the return address.  It is nanovx and NOT nanovAx.

ebersman@uunet.uu.net (Paul Ebersman) (02/22/91)

>> From: Greg Andrews; Re: Problems between T2500 and Hayes V series modems?:
greg> Posted: Thu Feb 21 20:19:28 1991

> In article <786@dynasys.UUCP> jessea@dynasys.UUCP (Jesse W. Asher) writes:
jesse> Has anyone had problems getting a T2500 and a Hayes V series modem
jesse> connected?  I'm having a strange problem - the modems connect but
jesse> connect at 300 or 2400 baud and sometimes the T2500 doesn't get a 
jesse> CONNECT message.  Anyone have any ideas on what could be causing this?

greg> I've seen this several times.  It only happens when the T2500 calls the
greg> V-9600, and the V-9600 is *not* an Ultra 96.  If the V-9600 calls the
greg> T2500, things are fine.  Setting S50=3 (limit the modem to V.22bis and
greg> slower modulations) in the T2500 takes care of the problem and the modems 
greg> connect at 2400 without a hitch.

This may be due to the leading v.25 guard tone before PEP, introduced
at GE6.00 on the T2500's. There are ways of changing this behavior.
Telebit tends to recommend going with a PEP last answer sequence, but
you can also vary the duration of the guard tone and when it is
presented. Call Telebit for details on the options that are best for
you.
--
                   Paul A. Ebersman @ UUNET Communications
                   uunet!ebersman or ebersman@uunet.uu.net
       The difference between theory and practice in practice is greater
           than the difference between theory and practice in theory.

gs26@prism.gatech.EDU (Glenn R. Stone) (02/23/91)

In <EBERSMAN.91Feb22104930@cfmartin.uu.net> ebersman@uunet.uu.net (Paul Ebersman) writes:

>>> From: Greg Andrews; Re: Problems between T2500 and Hayes V series modems?:
>greg> Posted: Thu Feb 21 20:19:28 1991

>greg> I've seen this several times.  It only happens when the T2500 calls the
>greg> V-9600, and the V-9600 is *not* an Ultra 96.  If the V-9600 calls the
>greg> T2500, things are fine.  Setting S50=3 (limit the modem to V.22bis and
>greg> slower modulations) in the T2500 takes care of the problem....

>This may be due to the leading v.25 guard tone before PEP, introduced
>at GE6.00 on the T2500's. There are ways of changing this behavior.

Umm, if that is what was happening, it was set to do that.... S92 is
0 by default (PEP tones first); a 1 sets PEP last, and a 2 turns
the V.25 guard tones on.  

>Telebit tends to recommend going with a PEP last answer sequence,

Yeah, me, too, if you're going to get calls from V.32 (or other CCITT)
modems.  My T1600's are much happier when they don't have to wade thru PEP to
get to the V.?? negotiation.... whilst another T2500 is set by
default to wait 40 seconds before giving up, more than enough time
to get to the PEP tones.... 

-- Glenn R. Stone
gs26@prism.gatech.edu

gandrews@netcom.COM (Greg Andrews) (02/24/91)

In article <22621@hydra.gatech.EDU> gs26@prism.gatech.EDU 
(Glenn R. Stone) writes:
>
>My T1600's are much happier when they don't have to wade thru PEP to
>get to the V.?? negotiation.... 
>

What do you mean by 'happier'?  The T1600 was specifically designed to
NOT be confused by PEP answer tones and any preceeding V.25 answer tone.  
I've made many calls from a T1600 to a T2500 and the T1600 always stops 
its own V.32 response tone when the PEP answer sequence appears.  When 
the real V.32 tones appear, the T1600 links up no sweat.

-- 
.-------------------------------------------.
| Greg Andrews      |   gandrews@netcom.COM |
`-------------------------------------------'

tnixon@hayes.uucp (02/25/91)

In article <145821@pyramid.pyramid.com>,
lstowell@pyrnova.pyramid.com (Lon Stowell) writes: 

>    It is unfortunate that the CCITT can't treat the "V" as a
>    trademark and sue the pockets off manufacturers who use
>    CCITT-like terms for their products...when in fact the
>    product is proprietary and couldn't talk to a REAL compliant
>    product if it had to.  
> 
>    Hayes makes good modems, but IMHO they deserve a resounding
>    slap right upside the head for naming a product such that the
>    technically uninformed buyer would assume that it in any way
>    could talk to a REAL CCITT modem at the advertised rate.

At least let me say "don't blame me!"  Before the Hayes V-series 
modems were announced, the "working name" was "Very Smartmodem", and 
lots of people inside Hayes still call them generically "Very" for 
short.  When the marketing types got hold of this, they said "naw, 
not catchy enough", and, somehow, same up with "V-series".  Well, I 
am _not_ "in the loop" for product names at Hayes, and when I 
finally was made aware of this, is was too late -- all kinds of 
commitments made.  Being Hayes' representative in the CCITT, I, of 
course, made it known that there would be considerable confusion 
with CCITT "V series" devices (the CCITT doesn't hyphenate it, if 
that makes any difference [of course it doesn't :-(] ).  Believe me, 
I've been throughly beat up about this by my counterparts from other 
modem companies, but I nevertheless continue to plead my innocense.  
There was sincerely NO attempt to cause confusion between Hayes 
V-series and CCITT V series; it's just that those who made the 
decision to change "Very" into "V series" were completely unfamiliar 
with the practice of referring to modems which comply with CCITT 
standards generically as "V series".

Doubt if you wish, but that's the Gods-honest truth.

	-- Toby

-- 
Toby Nixon, Principal Engineer    | Voice   +1-404-840-9200  Telex 151243420
Hayes Microcomputer Products Inc. | Fax     +1-404-447-0178  CIS   70271,404
P.O. Box 105203                   | UUCP uunet!hayes!tnixon  AT&T    !tnixon
Atlanta, Georgia  30348  USA      | Internet       hayes!tnixon@uunet.uu.net

root@zswamp.fidonet.org (Geoffrey Welsh) (02/28/91)

 >From: tnixon@hayes.uucp

 >Doubt if you wish, but that's the Gods-honest truth.

   I saw in a .sig (forget whose) something to the effect of "whenever 
there's a choice between ignorance and malice, the smart money's on 
ignorance".  I guess that applies to Hayes' choice of "V-Series" as a name...
 

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