[comp.dcom.modems] T-1600 Problem Already Solved!

ptownson@delta.eecs.nwu.edu (Patrick A. Townson) (06/03/91)

It is to the credit of this net that a problem can be presented before
I go to Sunday dinner, and be resolved for me when I come back an hour
later. 

I mentioned that BREAK would go into command mode on the Telebit
T-1600 and that I could return on line with ATO or ATO1 as needed. But
giving three plusses to go into command mode caused me to be locked
out when I later did ATO.

Aside from the fact that changing S-register values around in the
middle of an on-line session *can* confuse the modem and cause you to
get messed up, the problem it seems was that the host was also
responding to the three plusses.

I'd go in command mode, but so would the host ... and I'd come out of
command mode with ATO, but the host would pay no attention to me,
still being off line in its own environment.

Changing my escape code from plusses to tildes (~ ascii 127) did the
trick. Once done, to prove my point to myself, I went back on line and
issued three plusses. *My* modem ignored them this time, but the host
still locked up.

Not wanting to leave the host modem locked up in command mode, I tried
to figure out how to get it back on line, knowing it would not respond
to me telling it to do so (my ATO never made it through). So I played
a little trick:

   I wrote a shell script which did one thing: echoed 'ATO' when
   run.  I set up a crontab to go off one minute later which would
   execute the script ... 

   Then I handed three plusses to the host ... it froze, and I waited.
   About 45 seconds later the little job ran, and sent ATO in my
   direction .. the host modem saw it and opened up for business
   again!

But a better answer was to send a note to root at the server, with a
courtesy copy to root@eecs.nwu.edu asking them if they were aware they
had forgotten to disable the escape sequence from the dialup modems.

Thanks to the several of you who responded in email!


Patrick Townson