User conference: Embrace OPC Unified Architecture, says Yokogawa
' OPC Foundation tools are like a utility—a data pipe for sending information from one place to another—and those using automation to transfer data need to embrace OPC Unified Architecture (UA) to increase security and data integration,' was the message from Dave Emerson, principal systems architect at the U.S. Development Center of Yokogawa Corp. of America . Emerson made the comments as part of Yokogawa's Technology Innovations Fair and 7th Annual User Conference, held Nov. 29-Dec. 1, 2006, in Houston.
'UA use avoids point-to-point interfaces and hundreds of low-level drivers,' said Emerson, 'and OPC tools reduce related costs from a tangle of interfaces, allowing easier upgrades.'
The company feels that UA architecture—based on Web services, XML, and service-oriented architecture (SOA)—is needed because current OPC specifications are based on Microsoft DCOM, which doesn't work well with firewalls. UA adds more complex and structured data, reliability, security, performance, platform neutrality (Java, embedded platforms, and middleware beyond Microsoft offerings), and backward compatibility (through UA wrappers for DCOM clients and servers).
UA also offers integration with more applications, such as MES and ERP, to 'be a better IT citizen,' providing glue among various layers of devices and software in the plant, enterprise, and supply chain, Emerson said. He expects to see companion documentation from industry groups defining OPC UA 'transports.' IEC, ISA, MIMOSA are working on information model specifications. Subscription update features include keep-alive, heartbeat messages. Redundancy features, not in the original specification, also are being worked into UA.