Cheap or free auto-shutdown setup (was: Reliability Sys V file sys)

[Bill Vermillion]

In article <1990Sep29.220137.6550 at intek01.uucp-> mark at intek01.uucp (Mark McWiggins) writes:
->rdc30med at nmrdc1.nmrdc.nnmc.navy.mil (LCDR Michael E. Dobson) writes:
->[about a $250 autoshutdown monitor]
->
->Don't know why I didn't think of this sooner, but wouldn't a 300 bps
->external modem work just as well?  Send 'AT' every 30 seconds or so and wait 
->for 'OK' ... You should be able to get one of these modems really cheap at a 
->swap meet, or perhaps lying around for free.  If all else fails, new 300/1200
->externals go for $75 or less via Computer Shopper.
->
->This scheme would of course also work with any other doodad (program running
->on a nearby PC?) that has a separate non-protected power supply and knows how
->to respond to commands via a serial port.  Can't think of anything that would
->be as cheap as an old modem, but am open to suggestion on that.
->
->The shell script to listen on the port and do the shutdown seems trivial;
->I'll post a copy of mine when I get it done, unless somebody beats me to it.

Why couldn't you just use a cheap relay connected to the mains power
source.  Then connect pins 2 & 3 of the rs232 to a pair of contacts that
are closed when power is on.  Then just send something out and see if it
echos.  If it doens't come back to you, the power is off!

Or am I really overlooking something here?:
-- 
Bill Vermillion - UUCP: uunet!tarpit!bilver!bill
                      : bill at bilver.UUCP