Hi,

What about an alarm system based on RS-485 supporting up to 32 devices (even 128)
with maximal network length of up to 1500m?

With the master PIC you could:

- Query the status of the slave PIC.
- Reset the alarm status of the slave PIC.
- Turn the light on and off inside the room via slave PIC.
- .....
- .....

Also with the VB program talking to the master PIC via RS-232 you could
dynamically define areas which are protected also during the day and monitor/log
the activity of each slave and and therefore know which window/door you will
have to check before you leave the building.
What about verify the temperature of the air-conditioning in the computer server room?
There are no limits here.....

Best regards,

Luciano
Star Trek Security Systems