It is an open protocol that specifies the exchange of information for industrial communication.
OLE for Process control.
OLE: Object Linking and Embedding.
Exchange of process data, alarms and events, and historical data all from one client and server application.
Three key elements:
1. One should have the idea about the OPC foundation.
2. OPC Standard: OPC Classic vs OPC UA
OPC Classics standard is based on COM & DCOM, a product by Microsoft back in 90s. It was first released in 1996. This method was based on microsoft Distributed Component Object Model (DCOM) for client- server communications. While DCOM has certain authentican features built-in, it is not fully secure. It is hard to configure and usually requires operation intervention to correct when failure occurs.
OPC UA standard came out in early 2000.
3. Companion specifications are the specifications that tell you how to create user defined data type for a specific type of equipment/process. they call it information models.
(information is transformed data)
OPC Server is the unit which has the data
OPC Client wants the data.
OPC UA standard provides the guideline regarding how to build the OPC server.
PI interface collect the data from OPC DA. DA stands for Data Access.
so OPC DA is kind of a standard for data communication across the automation system.
OPC UA : OPC Unified Architecture; was developed in mid 2000 as TCP/IP - based protocol with the ability to share the data at control system level in real time with high reliability and efficiency.
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