DVR systems DVRxx04LE-A Series - Manual (Page 27)

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Please refer to the following sheet for alarm input and output connection. See Figure
3-5
Figure 3-5
There are two alarm input types for you to select: normal open (NO) and normal close (NC).
1. Alarm input
a. Please make sure alarm input mode is grounding alarm input.
b. Grounding signal is needed for alarm input.
c. When you are connecting two DVRs or you are connecting one DVR and one other device,
please use a relay to separate them,
2. Alarm output
The alarm output port should not be connected to high power load directly (It shall be less than
1A) to avoid high current which may result in relay damage. Please use the co contactor to
realize the connection between the alarm output port and the load.
3. How to connect PTZ decoder
a. Ensure the decoder has the same grounding with DVR, otherwise you may not control the PTZ.
Shielded twisted wire is recommended and the shielded layer is used to connect to the grounding.
b. Avoid high voltage. Ensure proper wiring and some thunder protection measures.
c. For too long signal wires, 120Ω should be parallel connected between A, B lines on the far end
to reduce reflection and guarantee the signal quality.
d. “485 A, B” of DVR cannot parallel connect with “485 port” of other device.
e. The voltage between of A,B lines of the decoder should be less than 5v.
4. Please make sure the front-end device has soundly earthed.
Improper grounding may result in chip damage.
3.7.1 Alarm Input and Output Details
This series product has two types of alarm ports. Please refer to the following two figures for
detailed information. There are two alarm input types for you to select: normal open (NO) and
normal close (NC).
Important
Please refer to the specifications for the alarm input and output channel amount. Do not
merely count the alarm input and out channel amount according to the ports on the rear
panel.