IT SKILLS

OPC-UA Averts Interface-Protocol Explosions

Calling OPC Unified Architecture (OPC-UA or UA) from Scottsdale, Ariz.-based OPC Foundation (www.opcfoundation.org) “very scalable,” Jeff Harding identifies two principal features that make it a communication mechanism across various protocols or standards: its ability to model complex things, and the basic set of services it provides.

UA provides basic infrastructure needed to create a client-server-based system, explains Harding, chief software architect of vendor ABB Process Automation Inc. (www.abb.com), Houston. Stressing that OPC-UA describes base services as well as a base object model, he says, “those services are defined for establishing secure connections with servers, reading, writing, eventing and calling methods, to name a few.” The services facilitate OPC-UA’s connectivity that spans vendors, legacy systems and the enterprise.

“Using a set of services this small avoids the typical explosion of interfaces and methods found in other connectivity solutions,” Harding remarks. That’s good, because “this explosion results in highly complex systems that are difficult to understand and maintain.” End-users can thwart explosions with UA, because each time a new data source is introduced, no new service is required, he continues. “The same services are applied to new data sources by using the discovery capabilities of OPC-UA.”

The object model presented to OPC-UA clients represents the other principal feature of UA’s overall functionality that allows communications between different technologies. Defined browse-and-query services “enable a client to ‘discover’ the server’s address space and object model,” Harding explains. Other standards build on that model, “exposing whatever information those standards have defined,” he says. Even unique operations defined by other standards but not covered by standard OPC-UA servers can be mapped to an OPC method, Harding adds... Read more

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ANNOUNCEMENT

OPC Foundation - OPC Seminar Toronto

The seminar will cover all aspects of OPC Technology including OPC Servers, OPC Clients, Alarm and Events, Historical Data Access and OPC Best Practices. The program will end with a presentation on the new OPC Unified Architecture. October 10, Toronto, Ontario.
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