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Alarm outputs on CCTV cameras are designed to be able to interact with third-party equipment, such as: barriers, automatic gates, security alarm systems, etc.

There are two types of alarm output control on Trassir/ActiveCam cameras:

  • active voltage between contacts "OUT" and "GND"

  • dry contact - The word "dry" means that there is no voltage at the dry contact terminals if the terminals are not connected to other equipment.

    It is assumed that, in addition to the absence of voltage sources in the dry contact circuit, the dry contact circuit is galvanically disconnected from other external electrical contacts of the device.

Connecting cameras with an active alarm output
List of camera models related to this type of alarm output:







































Voltage between OUT and GND contacts: 3.3V (3mA)

The principle of operation of the active alarm output:
At the time of the alarm event (motion detection, sabotage, number recognition, etc.) on the camera output contacts(OUT) and on earth(GND) there is a voltage equal to 3.3 V and a weak electric current equal to 3 mA. (see pic.1)

pic.1 Alarm output contacts OUT and GND

It is difficult to choose a relay module that will be able to close with such a weak electric current, as an alternative, relay modules that can close with such volt-ampere characteristics of the camera can be used.

Consider as an example the relay module SR0039-12-1L-BOX (pic.2)

(pic.2) Relay module SR0039-12-1L-BOX

Connection diagram of the active alarm output to the relay module:
The alarm output of the camera is connected to the relay module as follows (pic.3):
1. The contact of the camera "OUT" is connected to the contact of the relay module "IN".
2. The contact of the camera "GND" is connected to the contact of the relay module "GND".

(pic.3) Wiring diagram of the alarm output to the relay module

Thus, when an alarm event is triggered, voltage will be applied to the relay module from the camera.

The module, in turn, will close the power circuit into which any executive element is connected (barrier, gate, alarm system, etc.).

Connecting cameras with dry contact
List of camera models related to this type of alarm output:

TR-D1250WD v2


TR-D2223WDIR7 v2TR-D2221WDIR4TR-D3221WDIR3 v2TR-D4251WDIR2 v2

TR-D2253WDIR7 v2TR-D2222WDZIR4 v2TR-D2221WDIR4W v2TR-D3223WDZIR3 v2TR-D8221WDIR3 v2

TR-D2252WDZIR4 v2TR-D2223WDZIR7 v2TR-D2221WDIR4W v2TR-D3253WDZIR3 v2TR-D8251WDIR3 v2

TR-D2253WDZIR7 v2TR-D2224WDZIR7 v2TR-D2251WDIR4 v2TR-D4221WDIR2 v2TR-D9251WDIR3 v2

The maximum permissible values of current and voltage for power supplies, when connected to a dry contact: 12V (DC), 300mA

The principle of operation of the dry contact:
In the case of a dry contact, the camera acts as a relay (key). That is, when the camera receives an event to which a reaction should occur, the contacts "OUT" and "GND" close together inside the camera.

Wiring diagram of alarm outputs on cameras with dry contact:

(Pic.4) Connection diagram of the alarm output of the camera with a dry contact, with a performing element in the role of a light bulb

In this scheme (Pic.4), a light bulb is used as an executive element. When the camera detects an event, a short circuit occurs inside the camera between the "OUT" and "GND" contacts, as a result of which voltage is applied to the actuator from the power supply.
Any other elements can be used as an executive segment, such as: a siren; a barrier; an electric gate; a light bulb, etc.

Alarm inputs

Alarm inputs are designed to connect external sensors that are more highly specialized than the built-in camera sensors (for example, a motion sensor), or sensors that are not used at all in the built-in camera functionality (for example, a leak sensor).
Sensors are divided into two types Active and Passive, depending on the type of sensor, its connection scheme to the camera will change.

In passive sensors (for example, reed switch), no additional power is required, and accordingly, sensors of this type are connected immediately with one contact to the camera contact "IN", and with the other contact to the camera contact "GND".

As for active sensors, they implement more complex functionality, as a result of which they need to connect additional power. As a rule, such sensors have a separate power connector or power supply, and the connection scheme to the camera itself does not differ from the connection scheme of a passive sensor.

Volt-ampere characteristics of active sensors when connected to the alarm input:

For the first list of cameras with active alarm output: 3-24V (DC), 5mA
For the second list of cameras with dry contact: 3-5V (DC), 5mA

Alexander Savkin