Scene cascading

The Scene object offers the possibility to define a series of commands (see Standard Scene). Hence actuators can be controlled by the call of a scene. The specialty of the TwinCAT Building Automation Framework’s scene management is the possibility for one scene to call another. This scene can also be defined on another controller. The TwinCAT Building Automation Manager automatically creates the necessary network variables.

The following example shows how a building with several controllers automatically reacts to events with the aid of scenes. If the wind velocity exceeds a certain threshold value, all sunblinds are to be automatically driven upwards.

A useful variant is to create a scene on each controller that drives all the controller’s blinds upwards. The controller that evaluates the data from the weather station activates this scene on all controllers. The TwinCAT Building Automation Manager creates the necessary network variables on activation of the configuration. These are also optimized in such a way that the load on the network is minimal (e.g., using multicast network variables). Hence, all scenes in the building are activated in a simple manner to drive the sunblinds upwards.

A further variant involves the cascading of scene calls. In this example the cascading takes place over two levels. On each floor there is one controller that contains the scene with which all controllers on the respective floor are addressed. The controller with the weather station now no longer needs to call the scenes on all controllers. It suffices when the scene is called that activates all further scenes on the floor.

Cascading offers the possibility to react more flexibly to changes. If a certain floor is no longer to be included, this can be achieved by removing a single command from the scene in the controller with the weather station.