What is the specification for the alarm output GPIO for the IPIX Network camera?
The alarm output GPIO circuit consists of the collector and emitter of an opto-isolator. A voltage bias is required across the collector (Alarm Out +) and the emitter (Alarm Out -) ports to output an alarm from the camera. Note: ALARM_C and ALARM_E on the diagram above corresponds to the Alarm Out + and Alarm Out – respectively on the camera’s interface connector. When the camera causes an alarm, the transistor conducts current from the Alarm Out + to the Alarm Out – outputs. In typical use, the Alarm Out + pin is tied to a voltage source, or the Alarm Out – pin is tied to ground. The other, unconnected, pin can be resistively biased (to prevent over current), and fed to a voltage or current sensor (such as the input to a logic gate, or the base of a higher power transistor).
