Clusters

A cluster is an application message type defined within a profile. You can use clusters to specify a unique function, service, or action. The following examples are some clusters defined in the home automation profile:

• On/Off - Used to switch devices on or off (lights, thermostats, and so forth)
• Level Control - Used to control devices that can be set to a level between on and off
• Color Control - Controls the color of color capable devices

Each cluster has an associated 2-byte cluster identifier (cluster ID). All application transmissions include the cluster ID. Clusters often have associated request and response messages. For example, a smart energy gateway (service portal) might send a load control event to a load controller in order to schedule turning on or off an appliance. Upon executing the event, the load controller sends a load control report message back to the gateway.

Devices that operate in an application profile (private or public) must respond correctly to all required clusters. For example, a light switch that operates in the home automation public profile must correctly implement the On/Off and other required clusters in order to interoperate with other home automation devices. The Zigbee Alliance has defined a Zigbee cluster library (ZCL) that contains definitions or various general use clusters that could be implemented in any profile.

XBee modules implement various clusters in the Digi private profile. You can also use the API to send or receive messages on any cluster ID (and profile ID or endpoint). For more information, see Explicit Receive Indicator - 0x91.