ct hangs forever

[Alex Martelli]

I have the following setup: a Telebit T1000 connected to an HP 9000
model 340 running HP-UX 6.2 (HDB uucp) through a switching thingie 
called MNET.  Everything works (more or less) acceptably, EXCEPT...

When the machine calls a remote terminal with ct, and the line drops
for any reason, ct never dies - it stays on, never releasing the
line nor its lock file.  Looking at leds when this condition obtains
shows the modem apparently quiet and well-behaving, BUT it must be
doing something funny because the MNET control box has flashing leds
and inoperative - I believe this means the modem is sending lots and
lots of BREAKs... killing the ct process, either with -1 or with -9,
does not seem to yield any result, nor does resetting MNET itself -
it starts flashing again at once.  The ONLY thing that helps is
turning the modem off, then on again: this restores things.

Modem and computer are connected only with Rx, Tx and ground, these
being the only signals MNET will pass.  I'm not sure how they are
supposed to communicate in general, but it works fine with cu or
uucico... is it because in this case the computer "KNOWS" when to
cut its modem link?  Even supposing I set up a kludge, so that the
ct session will be deemed to have ended anyway if, say, the line
has been inactive for 30 minutes, what can I then do at the computer
end to reset everything properly, in particular the T1000 modem,
short of getting some robot arm to flash its power switch off and
on again?-)  Working at the console, I have been unable to reset
things properly via software - only cycling the modem power helps,
although the modem itself, judging from its LEDs, would *appear*
to be good and quiet... any help or hints will be appreciated, I'm
just a poor software engineer out of his depth in this world of
telecomms and system administration!
-- 

Alex Martelli - Email: staff at cadlab.sublink.org, alex at am.sublink.org
Phone: ++39 (51) 371099, ++39 (51) 250434; fax: ++39 (51) 366964