Scenes: Overview and How They Work

A scene is a configurable state of one or more controllable elements. The term scene alone is not precise enough, so more specific terms are used below to make clear which aspect is meant. X2B can handle scenes both internally (technology-independent) and via KNX, and mixed if required.

For this, X2B provides two controls: the scene controller (holds the scene composition and states) and the scene button (activates or learns scenes).

Central to scene control is a scene number channel. This can be an internal channel or a KNX channel (in KNX usually referred to as a scene object). Each time the scene number channel is updated with a valid scene number (1-64), the scene is activated. If a negative scene number is received, an attached scene controller saves the current state for this scene number ("learning").

Required Objects and Their Function

Scene number channel: A channel via which commands (scene numbers) are sent and received. This can be a KNX channel (17.001 or 18.001) or an internal channel (virtual interface).

Scene controller: An X2B control in which the scene composition is configured, as well as which scene number channel controls the controller. If only KNX scenes are to be controlled, no scene controller is required (the scenes must then be programmed entirely on the KNX side). A scene controller saves one state for its scene composition per scene number and restores this state for the composition on demand. The controller receives the command to save (= learn) or restore (= activate) the state via the scene number channel.

Scene button: A simple X2B control that outputs commands (scene numbers) to a scene number channel. The scene button must be linked to a scene number channel, and the scene numbers are configured in the button.

Interaction with KNX

If the scene number channel is a KNX group address, it must be of data type 17.001 or 18.001 and should be configured as write-only (otherwise unwanted scene activations may occur when X2B/the KNX interface starts). When a KNX telegram is received, the scene number is converted accordingly and, if the "set" flag is set (18.001 only), the scene number is negated. When the scene number channel is written from the X2B side, the scene number is prepared accordingly for KNX and sent as a telegram. It makes no difference to X2B whether the group address is updated by a group read response or a group write. X2B only sends group writes.

Behavior:

For an invalid value (outside the range -1 to -64 or 1 to 64), no KNX telegram is sent.

Scene Controller / Composing a Scene in X2B

A scene controller defines the controls that belong to the scene. When a "learn" command is received (a negative scene number appears in the scene number channel), the scene controller saves the current state of the assigned controls under the scene number. When an "activate" command is received (a valid, positive scene number appears in the scene number channel), the scene controller restores the saved state for the scene number.

If the scene controller has not saved a state for a participating control, the control remains unchanged (nothing happens). This occurs if the scene number has not yet been learned or if the scene composition was changed after a scene number was learned. If a control is removed from the scene composition, the scene controller no longer controls it when a scene is activated, even if the scene has learned a state for the control.

If a scene controller is deleted, all scene data saved by this controller is lost as well.

Scene Button / Activating and Learning Scenes

A scene button can be used to activate or learn scene numbers. Since a scene button can activate a maximum of two scene numbers, several scene buttons may be needed to activate all scenes. To learn scenes, assign a learn command to a scene button, establish the desired state and then press the scene button. There is currently no way to edit a scene directly.

Controllable Controls