2.7.5 Alarm input and output connections
Alarm input
A. Alarm input is grounding alarm input.
B. Alarm input demand is the grounding voltage signal.
C. When the alarm is connected with two DVRs or connected with DVR and other equipments, it should be
isolated by relay.
Alarm output
Alarm output can not be connected with high-power load (no more than 1A).When forming the output loop it
must prevent the big current from relay damage. Use the contact isolator when there is a high-power load
PTZ decoder connections
A. The grounding of the PTZ decoder and DVR must be shared otherwise the common-mode voltage will
lead to the PTZ control failure. The shielded twisted pair is recommended.
B. Avoid the entrance of high voltage. Make the layout reasonably. Take precaution from the thunder.
C. In the outlying end connect 120Ω resistance paralleled to reduce the inflection and insure the signal
quality.
D. The 485 AB lines of DVR can not connected with other 485 output equipments paralleled.
E. The voltage between the AB lines of the decoder must be less than 5V.
Front equipment grounding note
Bad grounding can lead to the burnout of the chip.
Alarm input type unlimited
The DVR alarm output port is constant opening type.
(1) alarm input (2) grounding (3) RS232 (4) alarm output (5) RS485
485communication interface which is
connected with the recording control
equipments such as the decoder
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