The standard is divided into five parts. The first describes terms, definitions, functions, object structure and messages. Part 2 describes object attributes, while Part 3 offers a model of operational activities, including overall equipment effectiveness.
Part 3 can be used to detail function processing. “Part 3 is not so much about objects crossing over to ERP (enterprise resource planning), it’s more a dictionary of what’s happening inside the MES (manufacturing execution system),” says Jay Jeffreys, marketing director for automation software vendor Wonderware’s Third Party Programs, in Johnson City, Tenn.
Parts 4 and 5 respectively describe operations and message requirements. Though the standard has been in development for several years, ISA-95 is constantly evolving.
“Part 5 just received ANSI (American National Standards Institute) approval. It combines some of the work done in Parts 1 and 2, which are the nouns, and it adds verbs,” says Keith Unger, principal consultant at Stone Technologies, in Chesterfield, Mo., and chair of the ISA’s SP95 committee. The Open Applications Group helped in the creation of Part 5, Unger adds.
The standard doesn’t mandate specific implementations, though it does suggest best practices. That gives product and system developers the ability to tweak terminology for specific needs while still providing a platform that they can follow. By removing ambiguity in terminology, it reduces the chance that operations models and other higher-level plans will have inconsistencies.
Users note that while the potential for incompatibilities exists, that’s not a huge issue. “Even if all companies do is to standardize within the company, that’s a big step. It requires a bit of extra effort, but there’s a big payback,” says Rick Bullotta, a vice president at SAP Research, Palo Alto, Calif., who focuses on future manufacturing.
ISA-95 usage is seeing steady growth. “I’m being called on to teach more ISA courses, especially by people in aerospace and consumer and medical devices,” Jeffreys says. Those new to the specification may have a sense of deja vu—parts of ISA-95 are used by other standards bodies such as the WBF (formerly World Batch Forum), and there are many similarities between ISA-95 and ISA-88, a batch control standard.
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