how to detect voltage on a pin of the serial interface?

From: <emanuele.lombardi_at_casaccia.enea.it>
Date: Wed, 18 Oct 2000 10:45:19 +0200 (MET DST)

Hi alpha gurus,
 today I need to check the presence of electric voltage on a pin of the
 serial interface of a alpha machine running 5.0a.

 The reason is that my UPS five minutes before "death" zeroes the
 voltage on a known pin of the serial interface. I would like to have a
 daemon checking the pin and, as soon as there is no more voltage,
 broadcast a shutdown command to all my machine (via rsh or ssh).

 I guess a C program should be able to test the presence of the voltage
 on the pin, but I have no knolewdge about this topic so I ask your
 help.
 I only need a piece of code which returns 1 or 0 according to the
 voltage level on the pin. From that code I will (I hope) be able to do
 the rest.

Thank you very much,
Ciao from Italy,
Emanuele

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Received on Wed Oct 18 2000 - 08:47:20 NZDT