OPC UA Part 1 - Overview and Concepts 1.02 Specification(17)

OPC UA Specification Part1 OverView and Concepts

Release 1.02 9 OPC Unified Architecture, Part 1

Figure 2 – OPC UA Target Applications

OPC UA is designed to provide robustness of published data. A major feature of all OPC servers is the ability to publish data and Event Notifications. OPC UA provides mechanisms for Clients to quickly detect and recover from communication failures associated with these transfers without having to wait for long timeouts provided by the underlying protocols.

OPC UA is designed to support a wide range of Servers, from plant floor PLCs to enterprise Servers. These Servers are characterized by a broad scope of size, performance, execution platforms and functional capabilities. Therefore, OPC UA defines a comprehensive set of capabilities, and Servers may implement a subset of these capabilities. To promote interoperability, OPC UA defines subsets, referred to as Profiles, to which Servers may claim conformance. Clients can then discover the Profiles of a Server, and tailor their interactions with that Server based on the Profiles. Profiles are defined in Part 7.

The OPC UA specifications are layered to isolate the core design from the underlying computing technology and network transport. This allows OPC UA to be mapped to future technologies as necessary, without negating the basic design. Mappings and data encodings are described in Part 6. Two data encodings are defined:

∙XML/text

∙UA Binary

In addition, three transport protocols are defined:

∙OPC UA TCP

∙SOAP/HTTP

∙HTTPS

Clients and Servers that support multiple transports and encodings will allow the end users to make decisions about tradeoffs between performance and XML Web service compatibility at the time of deployment, rather than having these tradeoffs determined by the OPC vendor at the time of pr oduct definition.