Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!tektronix!percival!bucket!leonard
From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: comp.dcom.modems
Subject: Re: Dial-back modems
Message-ID: <1498@bucket.UUCP>
Date: 26 Jun 89 07:13:16 GMT
References: <43f20cbb.144c9@gtephx.UUCP>
Reply-To: leonard@bucket.UUCP (Leonard Erickson)
Organization: Rick's Home Grown Unix; Portland, OR
Lines: 29

In article <43f20cbb.144c9@gtephx.UUCP> fraserr@gtephx.UUCP (Ross Fraser) writes:
<Is there any way that a Hayes-compatible called modem can control the baud 
<rate used for a data call? My company uses a dial-back system for access to our
<mainframe with 2400 bps modems. I also have a 2400 bps modem in my PC, but want
<to force the data rate down to 1200 bps when I am using the PC for terminal
<emulation because of the high error rate at 2400 bps. When I am using the PC
<for file transfers with Kermit, 2400 bps is acceptable because the number of
<packets retransmitted is low enough to yield a higher effective transfer rate
<than with 1200 bps. 
<,
<My experience to date has been that the originating modem always requests a data
<rate, and the called modem will respond with a modem tone indicating the highest
<data rate it can handle (in my case 2400 bps). Setting my terminal emulator to
<1200 bps does not work because the modem does not seem to hand-shake with
<serial port until data synchronization has been achieved.

If you are originating a call, a "standard Hayes compatible modem" will not
connect at a rate higher than the rate the you are talking to it at. IE, if you
send the ATDT555-1212 string at 1200 bps your 2400 bps modem will not
shift up to 2400 bps if you call a 2400 bps modem. It will still fall *back*
to 300 if you get a 300 baud modem. 

So all you need to do is set your term program to make the call at 1200
bps.
-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short