Relay:
Safety feature - The relay keeps the state even in case of voltage loss. You can configure the default state of the relay (open/closed) via the DoorBird App. These connections can be used to connect an electric door opener or elevator call, for example. The device does not provide a power supply for an electric door opener. The power supply for an electric door opener must be installed separately.
Please note: If you wire an electric strike directly to the device, the electric strike could be tampered with by unauthorized third parties (e.g., by breaking open the device and short-circuiting the electric strike wiring). We therefore generally recommend the use of a remote safety relay mounted inside the house (e.g. DoorBird I/O Door Controller A1081) for wiring an electric strike.