OPC Unified Architecture (UA) is the latest standard from the OPC Foundation. Its purpose is to unify the OPC Classic standards of Data Access (DA), Alarms and Events (A&E), and Historical Data Access (HDA) into a single, extensible framework. At the same time OPC UA offers improved networking support, a more sophisticated security model, platform independence, and comprehensive information modeling.
The OPC UA spec allows for implementation across a wide range of hardware platforms and operating systems. The different OPC UA implementations that are possible within this extensible and flexible framework all share a common core OPC UA functionality and interoperability.
The goal of the DataHub program's implementation of OPC UA is to support the functionality most required for industrial process control—secure, real-time data communications. Currently this includes OPC UA Server and OPC UA Client support for Data Access, including Discovery, Address spaces, On-demand, Subscriptions, and Events.
The DataHub program offers its OPC UA Server and OPC UA Client support as fully integrated with all other DataHub features. This allows it to act, for example, as an OPC UA - Classic converter, to connect OPC UA to any SQL database, display and access OPC UA data via DataHub WebView, connect to Modbus or Excel, send emails, and support tunnelling OPC DA, server-to-server bridging, data aggregation, redundancy, and more.
Because OPC UA may be new to some DataHub users, this chapter includes background information on OPC UA, such as concepts related to Endpoints and Discovery, Certificates, and Security, while also providing the necessary instructions for configuring a DataHub instance to act as an OPC UA client or OPC UA server, along with some troubleshooting tips.