Contact closure

[bogusexception@xxxxxxxxx]

I have this crazy idea that...

1. I can use contact closure from a Home Depot style motion sensing
light fixture to provide a 120vac relay with contact closure-not
illumination.

2. With that contact closure on the relay I can use ________________
to inform a program running on my computer that the contact closure
has occurred. It doesn't have to be wireless. It could be serial
(distance ~60' to PC).

3. With contact closure sensed at the computer, a program running on
the computer would sense the signal, and act. I can write for Linux or
Windows, with .NET the preferred solution due to graphics for
monitoring.

I want to trigger actions on my audio port on the computer based on an
interim program that is listening for a signal/state to occur. Simple.

There are Rube Goldberg solutions out there with wireless, web, etc.
but this really doesn't need to be. Most every sstem-including the
risky/noisy X10 are designed to _send_ contact closures, not _receive_
them.

- I can solder a relay into a disassembled driveway motion detector in
2 minutes.
- I can run a contact closed pair to the PC.
- I _cannot_ convert that contact closure right next to the PC into a
signal that a running program/daemon can use as a trigger to act upon.

How can I convert a contact closure into a signal that a running
program can use?

TIA!

:)