Integrating various components of an automation system can cost up to ten times the price of just the components, depending upon the complexity of the system. This fact alone can destroy the benefits of an integrated system. The latest specification from the OPC Foundation—OPC UA—holds the potential of greatly reducing this cost penalty. All we need is for more suppliers to adopt the specification and make it available to those charged with implementing an integrated automation system.OPC DA (Data Access) has been an unqualified success moving simpler data from device to device and into databases integrated with enterprise systems. But the specification was growing old and needed a boost out of the orbit of Microsoft's component object model (COM) and distributed COM technologies and into the new world of operating system agnostic, Internet-enabled technologies. So, OPC Unified Architecture (UA) was developed. This specification enables even greater interoperability than the previous generation and offers greater security.Dennis Brandl, principal of BRL Consulting of Cary, N.C., and veteran of such standards committees of the International Society for Automation (ISA) as ISA88 and ISA95, was working with clients in the pharmaceutical industry to construct a system that would enable them to exploit benefits promised by the U.S. Food and Drug Administration's Process Analytical Technologies (PAT) initiative. The system involved connecting complex instruments such as analyzers, spectrometers and the like to the control system. Says Brandl, "This is really a big benefit to pharma companies because of the expected savings from PAT. You need to get visibility into the process."The problem is that the suppliers of these complex instruments each have their own interfaces. According to Brandl, the cost of integrating the various instruments could be up to ten times the cost of the equipment. While the instruments were different, Brandl says, "There are a lot of similarities. They all return one, two or three-dimension data with similar properties. A standard approach should work." So, they searched for standards. These instruments send quantities of structured data that the older OPC technology just didn't have the horsepower to handle in the time constraints required, but they discovered that OPC UA could do the job.A working group was commissioned that included representatives from three major pharmaceutical companies, several automation suppliers and Brandl to work on the analyzer device integration (ADI) specification under OPC UA. A draft specification has been written and is out for review. A reference implementation of the specification was demonstrated at the ACHEMA Exhibition in Frankfurt, Germany May 11-15 this year.Brandl adds, "As each end-user device gets smarter, we need a smart way to talk to it. Even though UA is based on Internet standards, the encoding is as efficient as the old OPC. Using XML can be wordy for some communication layers, but OPC offers an encoded version to make messages smaller. This makes overhead small enough that you don't even notice the message time. Plus you get the enhanced security of OPC UA."I have talked to people who are concerned that the UA specification has added complexity to what was a pretty simple specification. So, I asked Eric Murphy of MatrikonOPC, who also writes the OPC Exchange Blog, about that. He says you can still use legacy DA in UA. "One of the key requirements in OPC UA was to preserve the expected functionality from the classic OPC specifications," he adds. "The OPC Foundation already provides OPC UA proxies and wrappers, which allow OPC UA products and classic OPC product to communicate. Very little of OPC UA requires complex XML statements."Brandl concludes, "This is really useful and very helpful in positioning us as we move forward." I agree with him. We need this sort of interoperability if manufacturing is going to take the next leap forward in productivity, quality and profitability.For more information, visit the OPC Foundation Web site, at
www.opcfoundation.org.
