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December 2009

HMI standards writers weigh in on importance

By Maurice Wilkins

Ask anyone with experience in human-machine interface (HMI) design for their advice, and they will probably give you their opinion on the color scheme, how the operator should interact with it, and whether the color red is on or off or alarm. In fact, color is probably the biggest discussion point in HMI design, as a recent e-mail thread on the ISA101 list server indicated. Quite a few books and best practices recommend the best way to design and implement an HMI. So is a standard really necessary? The answer from industry is yes. The standards committee established to address the issue is ISA101.

Different takes on HMI

Dave Lee of User Centered Design Services and leader of the display types section said the HMI world is “like a collection of small frontier towns; individually they have tremendous resources, but are largely lawless, with the inhabitants creating their own environments. None of the inhabitants have been outside of their own town, so they think theirs is the only way. ISA101 is the new governor trying to bring some order to the chaos and enable the sharing of experiences between these isolated communities. Our role on the ISA101 committee is not to dictate what we believe is the best way to approach HMI design, but to provide conduits to recognized industry best practice.”

ISA101 is important because it provides “the human in the equation, an interface that enables them to draw correct conclusions,” said Bridget Fitzpatrick of Mustang Engineering, and leader of two sections in the ISA101 standard. With an education in chemical engineering, Fitzpatrick has worked on everything from process design and operations support to process control and optimization over the past 20 years. “Process engineering design only takes one so far. At some point, you have to rely on the human,” she said. One of her biggest success stories is showing real-time energy cost to the operator on their control system displays, rather than in an external business report at the end of the day or month. “It became a video game for operators, where they sought the best energy price score all day, every day,” she said. “This paradigm shift helped save those extra few percentage points that normally required daily nagging from engineers or was money lost entirely. There is nothing like providing the operators with the tools to effectively manage rather than just operate their systems. A best-in-class HMI can truly change how facilities are run.”

Mustang has always had strong HMI standards of their own, but as HMI lead for automation and control, Fitzpatrick has responsibilities for all HMI content, which generally includes tens of thousands of displays per year. She sees value in industry consensus standards as a sales and education tool on the concepts inherent in best-in-class HMI systems.

As a representative of a vendor of HMI products and software, Dale Reed knows the importance of ensuring capabilities required by the ISA101 standard align as much as possible with users’ needs and products features. Reed, an ISA Certified Automation Professional (CAP) and a committee member from Rockwell Automation, said every member of the committee “represents his or her company’s interests this same way.” Even though members come from different perspectives, they respect each others’ competing interests, he said. “But I also participate in the committee in my own job role, as a developer of software objects with code, graphic symbols, faceplates, and displays,” he said. “The ISA101 standard committee brings together end users, integrators, and suppliers from a variety of industries, who have learned a lot of lessons over a lot of years actually doing HMI projects and developing HMI products. I want to leverage all that experience to make the objects I am developing as useful, as easy to use, and as high quality as possible. I want to avoid the mistakes that others have made. I want an HMI checklist against which I can review and test my objects.”

ISA101 committee member Ruth Schiedermayer, P.E., became more involved in the work of the ISA101 committee, boning up on research literature concerning sound quality techniques. “I feel it is important for the field of automation to increase recognition of the impact of the sounds coming from the human-machine interface on human performance. References to sound quality techniques in sound selection criteria in the ISA101 standard can be used to guide the selection or recommendations I make in the future concerning the choice of sound files for auditory alerts,” she said.

“Since configurable HMIs were first introduced in the mid 1970s, there have been numerous attempts to standardize on display designs, colors, and actions. When larger companies still had central engineering groups, this was often in their realm. Those groups no longer exist, and the power and versatility of HMIs have increased by leaps and bounds, to the point where guidance is needed now more than ever. The ISA101 standard will identify things that must be done to ensure a safe and operable HMI. It will also identify recommended practices for those things that may change from industry to industry or site to site.”

Lifecycle approach

The ISA101 committee establishes standards, recommended practices, and technical reports pertaining to designing, implementing, using, and managing HMIs in manufacturing applications. It covers menu hierarchies; screen navigation conventions; graphics and color conventions; dynamic elements; alarming conventions; security methods and electronic signature attributes; interfaces with background programming and historical databases; popup conventions; help screens and methods used to work with alarms; program object interfaces; and configuration interfaces to databases, servers, and networks.

The committee had two important face-to-face meetings in 2009 in which it decided the standard will take a lifecycle approach providing the glue for all the sections of the eventual standard. The lifecycle approach, which is still under development, will also apply to all HMIs, whether they are new or being upgraded from older systems. The committee also decided the standard will be aimed predominantly at those HMIs that are configurable and part of production automation systems rather than the single screen displays that could be part of a single machine control system.

The level and breadth of interest from suppliers and end users indicates industry is waiting for the standard. The contents are appropriate, according to respondents to a survey of the contents of the standard by the entire committee. As co-chair, I want to make sure ISA101 really provides Human-Machine Interface 101 for those in the industry who need guidance and direction. Joe Bingham of AES Global Inc. is the other committee co-chair. The goal is to have the first draft available by the second half of 2010. For more information, visit www.isa.org/link/ISA101.

ABOUT THE AUTHOR

Maurice Wilkins (maurice.wilkins@us.yokogawa.com) is co-chair of the ISA101 Human-Machine Interfaces standards committee and vice president of Yokogawa IA global marketing in Carrollton, Tex.