From: James L. Paul (james@netcom.com)
Date: 08/14/92 

From: james@netcom.com (James L. Paul)
Subject: Re: Modem dial-in procedures needed
Date: Fri, 14 Aug 1992 22:38:54 GMT

On a slightly different topic, I ran into a not-so-obvious (at least to
me :) problem. I have my inittab set up for 19200 bps getty. If I turn
this off and kill the getty to use the modem for outdialing (as I often
do) I have to be sure to use the modem at 19200 before re-enabling the
getty.

Otherwise, if the last AT command to the modem was not at my getty speed,
incoming calls will connect but not communicate with getty, since the
modem's DTE speed doesn't match the getty speed. (A user connects, sends
a <cr> or anything to get the login prompt, but gets nothing, since getty
is is listening at 19200 and the modem is talking at the last AT command
speed. (Say, 2400.)

I solved this by setting things up so I always talk to the modem from my
terminal software (xcomm) at the getty speed. This way, the modem is
never remains inadvertently on the wrong DTE speed.

I haven't dug out my modem manual yet to see if I can set the DTE speed
to a non-changing value. (I know the DCE speed can, but I doubt the
serial port DTE speed can.) Obviously, my solution above requires hardware
flow control, since the DTE speed is faster than the modem can handle. 

-- 
James L. Paul

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