Connecting Alarm Input/Output - Dahua Technology IPC-HFW3841E-AS-0280B-S2 Quick Start Manual

Connecting Alarm Input/output

Alarm input/output is available on select models.
Connect alarm input device to the alarm input end of the I/O port.
Device collects different states of alarm input port when the input signal is idling and being
grounded.
Device collects logic "1" when input signal is connecting to +3 V to +5 V or idling.
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Device collects logic "0" when input signal is grounded.
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Connect alarm output device to the alarm output end of the I/O port. The alarm output is
open-drain output, which works in the following modes.
Mode A: Level application. Alarm outputs high and low level, and the alarm outlet is OD,

which requires external pull-up resistance (10 K Ohm typical) to work. The maximum
external pull-up level is 12 V, maximum port current is 300 mA and the default output
signal is high level (external pull-up voltage). The default output signal switches to low
level when there is alarm output (As long as the operating current below 300 mA, the
output low level voltage is lower than 0.8 V).
Mode B: Switch application. Alarm output is used to drive external circuit, the maximum

voltage is 12 V and the maximum current is 300 mA. If the voltage is higher than 12 V,
please use an additional electric relay.
Alarm input
Mode A
2
Quick Start Guide