UA Capabilities
OPC UA has been designed for scalability and supports a wide range of application domains, ranging from field level (e.g. devices for measurement or identification, PLCs), to enterprise management support. To achieve these design goals, the OPC UA standard provides a multi-layered architecture as shown in the following figure:
OPC UA is built on the following Infrastructure:
- Discovery which allows Clients to find OPC UA Servers, their supported protocols, security policies and other capabilities.
- Transport which defines protocol mappings that allow establishing a connection and exchanging well-formed messages between OPC UA Applications.
- Information Access which comprises the means to expose object-based Information Models in an Address Space and the Services to access this information.
- Security and Robustness, which are integrated into Transport and Information Access.
Information models are layered on top of this infrastructure. OPC UA specifies a number of base information models (DataAccess – DA, Alarms&Conditions – AC, and more) that define commonly used objects including both real-time and historical data variables and alarms. Industry standard models inherit from and further specialize the lower layer models they are based upon.
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Following is the catalogue of OPC UA Capabilities structured according to the layers and subsystems of the UA Framework outlined before. |
