Gleaning Efficiency from Global Standards

Reusable code and common language simplify process design.

Aw 4367 Standards10

Building airplanes and making chocolate seem to have little in common at first glance. Not only are the materials vastly different, but the processes are too. Airplane manufacturing is parts centric, and candy making is a batch process.

“But if you think about it, sending an order from an enterprise resource planning (ERP) system to a lower-level system and reporting consumption while you’re fulfilling orders are the same, regardless of the product you’re making,” notes Wade Harsy, president of Integrated Process Automation & Control Technologies, (IPACT), a systems integrator in Valparaiso, Ind., that installs Wonderware software. “It doesn’t matter if you’re making tires, candy, planes or plastic bottles.”

Harsy’s company has been able to exploit such similarities, thanks to the international standards that have evolved for automation over the past decade or so. “Using standards brings a lot of commonality that helps us tremendously in delivering and supporting automation systems,” reports Harsy. They cut development costs, shorten implementation, improve quality and streamline maintenance. These benefits prompted IPACT to join the growing ranks of manufacturers and equipment suppliers committed to international standards.

Because of this commitment while developing software for the Boeing 787 project, the integrator was able to reuse some of the non-proprietary subcomponents in similar software that it developed later for a chocolate manufacturer. “The ability to leverage prior work gives us more transportability from one application to another,” says Harsy. “It allows us to use a leaner staff on subsequent projects.”

As an integrator specializing in the enterprise-to-process boundary, IPACT relies heavily on communications standards that define variables and organize communications in this space. Among the most important are the ISA-95 enterprise-to-control system standard and the ISA-88 batch-control standard developed by the Instrumentation, Systems and Automation Society (ISA), in Research Triangle Park, N.C. “Not only are we using the right characters, we’re also using the right syntax and structure,” says Harsy.

Because ISA-95 establishes a general structure for data models, IPACT still must do quite a bit of custom work to apply those extensible markup language (XML) structures to specific plants. For this work, it turns to the Business to Manufacturing Markup Language (B2MML) being advanced by the WBF organization, an ISA affiliate. This standard builds on ISA-95 to offer further guidance in integrating enterprise-wide business systems with manufacturing systems. “[ISA-95] provides structure for the text of a message, but B2MML goes a step further by standardizing the nature of the use of the message,” explains Harsy.

These standards are supported by the manufacturing software that IPACT installs from Wonderware, a Lake Forest, Calif.-based unit of Invensys plc, London. “We adhere to standards that govern the internals of our products and describe the connections between levels two and three in Purdue reference model hierarchy,” says Jay Jeffreys, marketing director for third-party programs, at Wonderware. “That is, those connections to the ERP systems above us and the shop floor devices below us.” The standards include those promulgated by ISA and various open applications groups to define connections to programmable logic controllers (PLCs), intelligent transmitters and networks.

Rockwell Automation Inc., the Milwaukee-based automation vendor, also helps its customers benefit from standards. The company reports that it has given users a framework for batch logic by integrating the ISA-88 equipment phase model into its RSLogix 5000 PLC with its PhaseManager software. “This eliminates the need for additional programming between batch procedure and recipe management systems and programmable automation controllers,” says Mike Wagner, business development manager for Rockwell’s Global OEM Team.

The vendor also offers modular programming guidelines for developing and validating modules of code that are based on standard programming methods and models. Users can put these prepackaged modules “on the shelf” and insert as needed into their machinery and processes. This modularity can reduce engineering time considerably.

“Programming a traditional eight-axis cartoner—including start-up code, motion functionality, machine control, and HMI (human-machine interface)—typically takes around 600 hours,” says Wagner. “Using the modular programming guidelines for the same machine, coding time takes only 170 hours, a savings of approximately 400 hours.”

Besides giving integrators and software developers the ability to reuse definitions, structures and pieces of code, international standards also can streamline multiplant installations by giving
the disparate plants a common object model and vocabulary. So if you spend a little more time on translating everything at that first site into the common vocabulary that everyone understands, the installation at subsequent sites should go much faster.

Such an investment in time, however, requires discipline. “The temptation is to just start coding and swinging bits around to get that first site done as quickly as you can,” notes Jeffreys, at Wonderware. “But then you have to do the whole thing from scratch again at the next site.”

Fueling this temptation is the fact that these standards are relatively new and evolving. “Abstracting the requirements of each application and projecting them onto the model can be difficult until you get a fair bit of experience,” says Harsy at IPACT. It also can require discipline and commitment because many of the standards have not evolved to the point that they cover complex or unusual situations. The temptation is to go with a custom solution to the problem rather than thinking it through and doing the development work to apply the standard as best as possible.

Not only does taking the time to follow standards mean faster and cheaper installation of equipment and software, but it also makes it easier for large companies to maintain their processes across dozens of plants once the automation is installed. A common problem with custom applications in the past has been that typically only one person has known how to support them. When that person eventually leaves the company, no one knows how to take over the support.

Standards have changed the landscape because they are like maps. Building processes based on these “maps” gives a wider number of people access to the underlying systems. This is appealing to global companies like DSM, a 22,000-employee producer of pharmaceuticals, nutrients, industrial chemicals and performance materials based in Heerlen, the Netherlands. “We can move people from one plant to another, and they will be acquainted with every system that they encounter,” says Frans Moonen, senior process control engineer at the company’s Technology Competence Center in Geleen.

Among Moonen’s chief concerns are the standards for the logic and process instrumentation that promote safety and reliability. “We have now several classification standards that require the equipment, DCSs (distributed control systems) and PLCs to run with a specific reliability factor,” he says. “These standards help me to explain to software and maintenance engineers how to maintain the required reliability.”

To ensure that the standards and symbols expressing them are the same everywhere, the company has adopted those promulgated by ISA, the International Organization for Standardization (ISO), and International Electrotechnical Commission (IEC) in Geneva. “In general, all of the plants in our company are using the same kind of documents so that we can understand each other,” says Moonen. The result is that a technician from the Netherlands will know how to go about solving problems in plants in Indonesia or China.

Standards also give DSM’s staff a way of communicating complex problems to external sources, such as the engineers at Emerson Process Management, Austin, Texas, which provides the instrumentation and consulting services for the DCS systems that Moonen designs. “I need to explain to them exactly what my requirements are,” he says. And that’s not easy because he is an expert in his company's process, not in the vendor’s products. He finds that the standards ease the problem by giving both sets of experts the language to communicate with each other.

Even so, standards are evolving rapidly to keep pace with advancements in computer technologies. Consequently, the engineering staffs at most manufacturing companies cannot stay abreast of the advancements and the accompanying revisions in the standards. “So we go to a provider that does the work for us,” says Moonen. “We work with Emerson to implement these standards and use them in the company worldwide.”

Working with vendors to implement standards pays two kinds of dividends. First, the standards give the system a framework to evolve in an orderly fashion as new devices and software become available. Second, they cut the total cost of ownership for end-users.

They do so in three ways, according to David Emerson, a systems architect at automation vendor Yokogawa Electric Corp.’s U.S. Development Center in Carrollton, Texas. First, the standards allow vendors to exploit economies of scale by spreading their development and maintenance dollars over a much wider base of applications. Second, they remove cost from the vendor’s entire supply chain by eliminating a lot of low-level work that adds little to no value. An example is the writing of point-to-point interfaces in the early ’90s before OPC came along to provide a standard way of exchanging data.

The last way that standards lower the cost of ownership is to allow users to mix and match different suppliers’ equipment and use the best of breed for their particular applications. “Otherwise, either you’re tied into one vendor, or you have to do a lot of work to make different vendors’ solutions work together,” notes Emerson. He doubts that the plug-and-play concept will ever make sense at the ERP level, but the standards should make the interfaces configurable. And that’s a much better way to glean efficiency from global standards.

 

To see the accompanying sidebar to this story - "A Short History of Standards for Controllers" - please visit www.automationworld.com/view-3326

 

For more information, search keyword “standards” at www.automationworld.com.

 

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