Alarms

 

Most of our DVRs and NVRs have alarm output that support the ability to connect external devices such as alarms, beams, door contacts and lights. These are just a few things that you can connect to. The alarm outputs on the DVRs and NVRs can be configured to be triggered by an event, such as camera motion detection, door contact via an alarm input and crossing an analytic tripwire. Each alarm output of the DVRs and NVRs is a simple relay circuit that switches from one position to the other (from normally closed to normally opened).

 

The majority of our DVRs and NVRs have 4 alarm outputs on a terminal block located on the back of the case. Please check the specification for the model that you are interested in or preferably contact us first so that we can confirm how many alarm output ports your DVR or NVR has as some of our range of NVRs do not have any outputs on the back of the recording units.

 

DVR Alarm Output Overview

 

The alarm output ports on the back of the DVR are each labelled with NO C NC. The NO stands for normally opened, NC means normally closed, and C means common contact. When the alarm is in the non-triggered state, it is normally closed which means that the circuit is allowing current to flow from C to NC. When the alarm is triggered, the relay is enabled and switched from the normally closed (NC) to normally opened (NO) position.

 

Relays

 

From the back of the NVR or DVR there are alarm outputs, they are used to drive lower voltage items like alarms, beams, door contacts and lights. If you were looking to drive more powerful and higher voltage items like gates, garage doors and main lights, you would then need a base relay so from the back of the DVR or NVR the outputs would be connected up to the base relay and this would drive the gates, garage doors and main lights. When using relays there is an unlimited amount of units they can drive so the possibilities of what you can do with them is endless.

Respectway Limited, Merlin House, Station Road, Brompton-on-Swale, North Yorkshire, DL10 7SE, Tel: 01748 811991  Email. sales@cctvfirst.co.uk
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