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This article discusses the general concepts of layers in the 11073 object approach, including the object layer, association layer, and alternative association layers like Zigbee Cluster Library and BT LE.
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LayersandAlternative Application Layers Malcolm Clarke September 10, 2012
Object Approach Agent Object Manager Proxy Object Events Actions Get Set • The object approach of 11073 is a general mechanism to update values of all attributes from the object in the Agent to its proxy object in the Manager • This can be done asynchronously (Events) or by polling (Get) • Can also act on the object to update attributes (Set) or interact (Actions)
Layers - ACSE Associate, Release, Abort APDU • This is achieved using physical connection and exchanging APDU between peer entities in the ACSE (Association Control Service Element) • ACSE is responsible for association and messages are exchanged for Associate, Release and Abort
Layers - ROSE Get, Set, Event, Action Methods PDU Associate, Release, Abort APDU • Once associated, PDU are exchanged between peer entities in ROSE (Remote Operation Service Element) • ROSE is responsible for providing METHODS to access and manage Objects and messages are exchanged for Get, Set, Event and Action
Layers – Object Layer Attribute values { Parameters PDU Get, Set, Event, Action Association Layer Methods PDU Associate, Release, Abort APDU • ROSE operates on peer objects in the Object Layer • ACSE and ROSE constitute the Association Layer
11073 Object Layer Methods (Get, Set, Event, Action) Parameters (Attribute:Value) • Objects in 11073 are accessed indirectly • Each object is referenced by its Handle and the type of the object is taken from the type attribute • Each attribute is accessed by using its nomenclature code (32 bits – 16+16) • The type of the attribute is defined by ASN.1 and structured types fully defined down to basic types • This has the advantage of allowing multiple instances of the same object type
Alternative Association Layers • Several “transport” technologies now define and support an object oriented approach and provide primitives to access and manage objects (methods) • Zigbee defines the Zigbee Cluster Library (ZCL) • BT LE defines ATT and GATT • Could these alternative Association Layers support 11073 objects and methods?
Zigbee Cluster Library • Supports • Discover Attributes • Read Attributes • Write Attributes • Report Attributes • Configure reporting • Min/Max time between reports • Min change between reports • Read Reporting Configuration
Zigbee Cluster Library • Defines • Attribute Clusters (eg General, Power configuration) • The collection of clusters defined as a profile • Attribute Sets in the cluster (eg Basic device information, basic device settings) • Attributes in the set • Currently 12 bits used to identify the Attribute Set and 4 bits the attribute within the set • Up 1000 addressable Attribute Sets (objects) each with up to 16 addressable attributes
ZCL Object Layer – exampleGeneral Attribute Set Attributes of Basic Device Information Attribute Set
Zigbee Cluster Library • Can we map 11073 devices to ZCL?
ZCL Object Layer – take an exampleWeighing Scale Attribute Set Attributes of Basic Mass Attribute Set
Limitations • Not instance based addressing
BT LE Attributes • BT LE also defines 16 bit attribute identifiers • Provides Object Access Methods • Object.Attribute could be defined for each device and correspond to specialization (ConfigId) as per ZCL • Object.Attribute Sets in the cluster (MDS, Metric Objects) • Attributes in the object set defined per MDS or Metric Object