Role of OPC in Interoperability and Data Connectivity

A modern factory is usually equipped with components from different vendors and with the advent of Industry 4.0 and digital transformation, there is a dire need to share data of equipment right from the plant floor to the enterprise level for OT (Operational Technology) and IT (Information Technology) Integration. However, there is a challenge of interoperability, reliability and security. OPC, an industrial open connectivity standard, is used to establish interconnectivity in different environments. It solves the problem of Automation’s data connectivity. How OPC resolves the data connectivity challenge is discussed in this LinkedIn article.

Manufacturers use proprietary protocols to exchange data among their own designed products and requires custom drivers to exchange information with other manufacturer’s products. OPC provides vendor-independent communication by abstracting the implementation details of Data Source and Data Sink from each other. An example of the data source can be a PLC while there can be multiple data sources like HMI, SCADA, Historian etc. OPC overcome the challenge of proprietary protocols by making it unnecessary for the Data Sink to be aware of how the Data source communicates or organizes its data.

If an HMI needed to communicate with a PLC, it required a custom HMI driver written for the specific protocol used by the PLC, if a historian needed to acquire the data from PLC, another specific driver would be needed. OPC eliminates the need for custom driver between each new application and Data source. Each Driver establishes its own connection to the data source for acquiring information, and different applications could request the same information using different paths which will increase the traffic for the data source. This device loading is effectively reduced by OPC because a single Device specific OPC connector requires only a single application to the Data source while simultaneously communicating with many applications. Also, in most of the cases OPC provides backward compatibility and avoids obsolescence of legacy infrastructure.

Initially, OPC launched as OPC Classic which are different interoperability standards like OPC DA (Data Access), OPC HDA (Historian Data Access), OPC A&E (Alarm and Event), however, they were based on Windows COM/DCOM Technology and OPC was OLE (Object Linking and Embedding for Process Control). The newer standard is OPC UA which is platform independent and more secure and reliable. It is now platform independent and can be embedded in the data source itself. Now OPC is Open Platform Communications which UA stands for the Unified Architecture.

References: Whitepapers from MatrikonOPC, Software toolbox and OPC Connect.