fraserr@gtephx.UUCP (Ross Fraser) (06/20/89)
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. , I have requested that the company set up two dial-back numbers - one at 1200 and the other at 2400; but am not optimistic that this will be successful. -- Ross Fraser @ AG Communication Systems, Phoenix AZ uucp ...!asuvax!gtephx!fraserr
leonard@bucket.UUCP (Leonard Erickson) (06/26/89)
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