I need to interface my Arduino with the base station of an alarm system. I have the following outputs to work with:
Terminal 1: +12V Common
Terminal 2: Zone 2 Open Collector Output
Terminal 3: Zone 1 Open Collector Output
Terminal 4: External Sounder Output
Terminal 5: Ground
I know this a a newbie question and I have been reading about Open Collector Output, but I'm not sure how to apply it to the Arduino. Basically, when the alarm is tripped, I need the Arduino to read the output in the most basic way (like a simple switch). It is a 12V system.
The 12V output needs to go to a voltage divider, to drop the value to 5V. Then, connect the two zone outputs to digital pins on the Arduino, with pullup resistors enabled, and see what you read when the alarm is and is not tripped.
An open collector output can be directly connected to the arduino input pin and then either use an external pull up resistor to +5V or enable the internal ones. You also need to connect the ground of your system to the ground of the arduino.
The fact that it is a 12V system does not affect output signal which just pulls down.
