Foscam FI9928P User Manual page 66

There is a Alarm In/Out lines in the FOSCAM camera tails, as shown in the following picture. Enable sound
detection need this cable to connect to the alarm device (door sensor, infrared sensor, smoke detector, etc.).
Alarm In/Out lines has four ports:
Port 1 indicates IO alarm input

Port 2 indicates GND

Port 3 and port 4 indicate IO alarm output

IO Output
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