Axis VANDALPROOF 3 User Manual page 84

If you select "N.O" in "Input sensor setting", when external
devise or circuit makes DI and GND pin connected, the
camera input alarm is triggered, and then camera will execute
the action user has set, for example, send snapshot to E-mail
address.
If you select "N.C" in "Input sensor setting", when external
devise or circuit makes DI and GND pin disconnected, the
camera input alarm is triggered,
and then camera will execute the action user has set, for
example, send snapshot to E-mail address.
c. I/O PIN definition
• GND (Ground): Initial state is LOW
• DO (Digital Output): DC 5V
• DI (Digital Input): Max. 50mA, DC 5V
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