Friday, January 16, 2015

OPC Enables Best of Breed Solutions

Posted by KyLeigh Corrigan

Before the introduction of OPC, client software vendors were responsible for writing their own device communication drivers. Any time an application needed to access data from a new device, a new driver had to be written. This approach worked fine when each vendor included all the connectivity requirements that their end users needed. But when they did not, end users were stuck with inaccessible silos of data.

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The first glimpse of hope for both client software vendors and end users alike was Microsoft’s Dynamic Data Exchange (DDE). DDE enabled users to aggregate their process or plant data into one application like Microsoft Excel. DDE’s limitations were quickly realized. It did not work across a network, had limited bandwidth, was not robust, and used a lot of system resources. A number of software companies attempted to fix these shortcomings but they remained proprietary and would never become a true industry standard.

The OPC Foundation

Recognizing this issue, in 1994, a group of vendors (Fisher-Rosemount, Intellution, Intuitive Technology, OPTO 22, and Rockwell Software) got together to brainstorm alternative solutions to the existing closed, proprietary communications model. The group’s goal was to define a common interface that could be written once and then reused by any client application. Leading automation suppliers worked with Microsoft to write the first standard, specifying the communication of real-time plant data from control devices from different manufacturers. This specification was called “OPC Data Access,” and allowed software developers to write vendor-neutral software.

This specification defined a standards-based communication technology based on a client/server architecture. It was soon decided by industry that this specification should be managed by an independent, non-profit organization that would be called the OPC Foundation. A major goal of the OPC Foundation was to develop additional industry standards that would continue to eliminate the need for client software vendors to develop their own proprietary communication drivers.

OPC Technology

With the OPC specification came the creation of OPC servers. OPC servers provide a method for any OPC client to access data from devices connected to the server. This new division allowed software vendors to focus on creating a friendly user interface with nice graphics and visualization while server software companies focused on creating seamless data source connectivity and interoperability with other software applications—thus providing a best of breed approach.

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The adoption of OPC technology reduced burden to client software vendors, letting them focus their efforts on the development of their client application. Adding the server layer between the client applications and devices also reduced burden to the devices themselves. Previously, multiple clients would make the same requests for the same data to the same devices. Now, the server bridges communications from the client to the device and is smart enough to maintain only one connection per device!

Kepware is an active member of the OPC Foundation and develops and maintains their products according to the OPC Foundation's specifications. OPC has allowed automation suppliers, like Kepware, to provide solutions that are truly open. This has given users more choices in their automation applications. OPC, which now stands for Open Platform Communication, lends itself very well to many industries, such as Manufacturing, Power, Oil & Gas, Building Automation & HVAC, Pharmaceutical, Big Data, and more. 

Learn More

Learn more about the history of the OPC Foundation and OPC specifications in the "Understanding OPC: Open Connectivity via Open Standards" whitepaper by Kepware's CEO Tony Paine.

Download Kepware's Understanding OPC eBook