OLE™ for Process Control (OPC) is a standards-based approach for connecting data sources (e.g., PLCs, controllers, I/O devices, databases, etc.) with HMI client applications (graphics, trending, alarming, etc.). It enhances the interface between client and server applications by providing a universally supported and well-documented mechanism to communicate data from a data source to any client application. Included are not only a detailed guide on how to pass the data, but also specific information on other attributes to supplement those data, such as range information, data type, quality flags, and date and time information.
OPC UA or "Unified Architecture" unites legacy OPC standards such as OPC-AE (Alarm & Events), OPC-DA (Data Access), and OPC-HDA (Historical Data Access) into one complete specification. The GENESIS64 automation suite supports these legacy protocols transparently, which incorporates newer communication standards while retaining backwards compatibility.
The figure below shows the OPC Architecture, which was introduced by the OPC Foundation. By following the OPC Architecture, a device needs only one standard driver, which is an OPC-compliant server. All OPC-compliant client applications can then be connected to that device, either locally or over a network. Furthermore, connections can be made to more than one OPC server at the same time.
OPC Architecture
Any OPC client application can connect to any OPC server. In other words, OPC offers true Plug-and-Play capability in the fields of HMI and industrial automation. OPC server types include OPC Data Access (DA), OPC Alarm and Events (AE), and OPC Historical Data Access (HDA).
The AlarmWorX64 application, which has both client and server components, is an example of a real-time data display where the focus is on alarm and event type data that is specified by the OPC-AE standard. You can configure AlarmWorX64 to display real time alarm events inside a viewer application that originates on an alarm server application that is monitoring alarm-based OPC-AE devices.
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