OPC: The next generation

Open connectivity through open standards began as a way for suppliers to achieve interoperability from factory floor devices to first-tier visualization applications. This is part of a Control Engineering December cover story.

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Open connectivity through open standards, known today as OPC, began in 1995 as a way for suppliers to achieve interoperability from factory floor devices to first-tier visualization applications. Based on Microsoft technology, OPC was a vendor-driven initiative.

“Vendors were tired of developing software to communicate to hardware on the factory floor and having to maintain all the corresponding device drivers,” explained OPC Foundation’s Tom Burke. “The situation aligned with the concept of a printer: printer companies provided corresponding software to allow applications to connect and print documents to the desired printer. In the OPC world, we created a cottage industry in which software companies began to develop software that performed better than that created by the hardware vendors for their respective devices.”

This model continues with OPC Unified Architecture (OPC-UA). “OPCUA,” Burke went on, “separates the data from the services in such a way that the data, and the corresponding metadata behind the data, can now be generically discovered by applications connecting up to devices or other applications, providing timeless durability for systems built today and tomorrow.”

End-user demands for security and reliability continue to drive competitive vendors to work together to develop industry standards such as OPC-UA. Consortiums are also working with the OPC Foundation to develop companion specifications that will plug into OPC-UA for their respective information models. “OPC provides the infrastructure necessary for discovering, querying, subscribing, reading, and writing information of the various consortium modeling activities,” said Burke. “Their suppliers can develop complex applications simply, without needing intimate knowledge of the information models that exist today…or will exist tomorrow.”

A simple example of this concept is the USB (universal serial bus), which has helped shape the consumer electronics world. “Plug a device in to a laptop that supports USB,” Burke explained, “and suddenly you are able to do everything with that device. Industrial automation systems of tomorrow will support the same plug-and-play operation. Applications will be able to discover the devices that are being plugged in and configure, diagnose, and retrieve data from them.”

www.opcfoundation.org

- Jeanine Katzel for Control Engineering, as part of the December 2010 Cover story: Integrating Disparate Control Systems.