Serial answering and dialing out

Serial answering and dialing out

Post by Frank McNamar » Sun, 24 May 1998 04:00:00

Do any of you know how to setup a serial port so that one can ring into
it, and then get it to call out (i.e. call me back).

I wish to be able to set up process control systems like this.

Many thanks - Frank McNamara


1. dial-in over a serial line, some answers

Hi, I've seen a bunch of articles asking about dial-ins over serial lines
and problems.  We've been having problems also, but seem to have solved
them.  Maybe this will help people, and maybe someone can point out the
inevitable flaws in our thinking, heh.

Anyway, we have a line in /etc/inittab saying
m1: 6:respawn:/bin/getty ttyS0 2400
at this point we are testing with a 2400 baud modem.

The modem itself needed to be fooled around with a bit.  Echo has to be set
off (ATE0), and modem response turned off (Q1).  With modem response not
turned off we were apparently having the modem attempt to log into itself.
The "RING" message looked like it was spawning getty before the modem even
picked up.  Pick up on ring 2 (SO=2).  (&D2) hangs up the line when the
user logs off and return to command mode in the modem.

This works for us.  Next up to bat, TCP/IP, fun fun...


Paul Fly                | "Thinking is more interesting than knowing,

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