Building a Better HMI

Nov. 2, 2012
Web-based technologies and interface design are just two areas in which consumer electronics technology is driving changes in industrial machine interfaces.

Portable equipment is transforming the way industrial workers monitor equipment and gather data. But for the foreseeable future, these handhelds will augment, not replace, the human machine interfaces (HMI) that are tightly linked to industrial machines.

These HMIs are advancing rapidly, using color displays, touch input, enhanced programmability and other technologies to make it easier for operators to set up and use complex machines. One of the most dominant trends in these controls is their utilization of commercial technologies. As they’ve done with the Ethernet communications that link systems together, developers are utilizing the huge volumes and vast knowledge base of electronics used by consumers, students and businesses.

“We’re seeing a lot more Web-based technologies,” says Gordon Daily, product marketing manager at Rockwell Automation (, Milwaukee. “Many HMIs offer shortcuts, navigation history and other elements people are familiar with from Web browsing.”

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HMIs also utilize commercial hardware, ranging from the microprocessors that work in the background to displays and inputs that operators see whenever they use the machine. Improvements in low-cost flat screen displays continue to help operators get more input without sacrificing readability.

“High brightness, high contrast, and multi-touch displays are certainly making operator’s lives easier. Higher resolution displays make reading and fitting a higher level of detail in graphs and images much easier,” says Dan Fenton, control and software marketing specialist at Phoenix Contact (, Harrisburg, Pa.

However, some developers feel that the capabilities of these displays have been overused. If there are too many options or too much information on the screen, it can create confusion instead of simplifying operation. When HMIs and portable equipment use imagery that isn’t identical, it can be even more confusing.

“HMI screens have gotten so colorful and complex that they’re difficult to use,” says Benson Hougland, vice president at Opto 22 (, in Temecula, Calif. “We’re working on techniques that make it easier for engineers to create screens that have different targets, like PCs, smart phones and tablets. It’s kind of like an app store. Making an HMI that’s easier to use is Opto 22’s number one R&D project.”

One way to reduce confusion is to let operators set up functions that are specific to their jobs. Developers are taking many different paths to help operators create these shortcuts. The code that works behind the scenes lets them make changes without impacting reliability.

“The software engineers who work on this code understand both the need for personalization and the requirement for reliability,” Fenton says. “Hiding a button because ‘it clutters your screen’ might not be possible, but changing how the button looks sure is. This makes certain the operator can always use that button if need be, as opposed to hiding it and then being unable to find it just when it’s needed.”

HMI creators are also following another industry trend, the move to develop all aspects of a system simultaneously. Many companies are working on the controls while the equipment is being designed. This ensures that the HMI operates with maximum efficiency.

“Companies need to focus on the back end code, so that the HMI is more tightly integrated into the system, rather than tacked on at the end,” Fenton says. “There is, of course, the drive to connect the mobile market, but I think what is holding this back more than anything is the knowledge of how to create a solid, reliable, and secure connection between the user and the machine the user is controlling.”

Terry Costlow is a Contributing Editor to Automation World,