Dahua HD IR Vari-focal Bullet Network Camera Quick Start Guide
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Mode A: Level application. Alarm output high and low level, alarm output is OC; it needs to
increase pull-up resistance externally to work normally. Max external pull-up level is 5V, max port
current is 5mA. After external pull-up resistance is increased, the default of output signal is high
level (external pull-up voltage), and it switches to low level when there is alarm output (when the
working current is 5mA, output voltage is less than 0.8V).
Mode B: Switch application. Alarm output is used to drive external circuit, max current is 30mA,
max voltage is 5V, it is advised to add a relay if it is beyond the value.