Digital inputs and outputs (I/O)
 The back of an AXIS 210 Network Camera with I/O connectors. |
A unique feature of network video products is their integrated digital input and output ports, which enable connection to external devices, such as doorbells, detectors (e.g. smoke, movement, sound, temperature and humidity sensors), lights (including infrared lamps), switches and alarm relays, and which are manageable over the network either from a remote PC or automatically using the camera's built-in logic. The I/Os can be used to eliminate unnecessary transfers of video; that is, unless sensors connected to the network camera or video server are triggered, no video is sent over a network.
When input and output mechanisms are triggered, you can manually or automatically request -- through the Axis network video product or an video management software -- that certain actions be performed over the network as well as through output ports. For instance, images saved from before, during and after an event (called pre- and post-alarm image buffering) can be immediately transferred over the network to specified destinations for recording and storage. At the same time, alerts to specific individuals via e-mail or SMS to a mobile telephone can be sent, and connected external devices such as lights, alarms and doors can be activated.
I/O usage example: A camera attached to a window switch and to an alarm system/siren
Digital inputs
The range of devices that can be connected to an input port of a network camera or video server is almost infinite. The basic rule is that any device that can toggle between an open and closed circuit can be connected to a network camera or a video server.
| Device type | Description | Usage |
| Door contact | Simple magnetic switch detecting opening of doors or windows | When circuit is broken (door is opened) the camera can take action, sending full motion video and notifications |
| Passive infrared detector (PIR) | A sensor that detects motion based on heat emission | When motion is detected, the PIR breaks the circuit and the camera can take action sending full motion video and notifications |
| Glass break detector | An active sensor that measures air pressure in a room and detects sudden pressure drops (can be powered by the camera) |
When an air pressure drop is detected, the detector breaks the circuit and the camera can take action sending full motion video and notifications |
Digital outputs
The output port's main function is to allow the network camera or video server to trigger external devices, either automatically or by remote control from a human operator or a software application.
| Device type | Description | Usage |
| Door relay | A relay (solenoid) that controls the opening and closing of door locks | The locking/unlocking of an entrance door can be controlled by a remote operator (over the network) |
| Siren | Alarm siren configured to sound when alarm is detected | The network video product can activate the siren either when motion is detected using the built-in video motion detection (VMD) feature or using "information" from a digital input |
| Alarm/intrusion system | Alarm security system continuously monitoring a normally closed or normally open alarm circuit | The network video product can act as an integrated part of the alarm system serving as a sensor and enhancing the alarm system with event triggered video transfers |
See other triggering mechanisms, such as:
