Efficient Plant November 2017 - 40

RMC

human-machine interfaces

CONSISTENCY

COLOR

Developing high-performance HMIs calls for restraint in design. Display only
what operators need to know, and make it easy to understand.

Quick Tips
For HMI
Development
ALTHOUGH DEVELOPING a human-machine interface (HMI) is
often the last part of a control-system-integration project, it's vital to the
success of an automation system. According to Justin Gilg of systems-integrator Huffman Engineering Inc. (huffmaneng.com, Lincoln, NE), a
successful HMI design requires restraint. He offered the following tips.
-Jane Alexander, Managing Editor

For more information regarding HMI development,
go to huffmaneng.com/5-tips-hmi-development/.

| EFFICIENTPLANTMAG.COM

In most cases, new HMIs should be modeled with the look and
functionality of others in use at the site. Consistency is key. If
the menu appears across the top of existing HMIs, follow that
format. The same goes for other aspects of the display. Uniformity is important for new-employee training and the operators'
ability to move to unfamiliar equipment.
Developing HMIs for facilities that don't already have them is
another matter. This situation allows more creativity, as well as
reliance on experience with similar applications. Consistency in
menu placement, color scheme, and graphics from screen to
screen is still crucial.

If the site has a standard for color, adhere to it. If not, there's
usually an industry standard. Limit the use of color so it captures operator attention. Colors designated for alarms should
only be used for that purpose. Color should not be the only
discriminator of an important status condition. Use text to call it
out. Complement the red-color button with the word "stop." To
draw attention to alarms and faults, add blinking. Don't overlook
the possibility of color blindness in operators. Red-green color
blindness is the most common type for males, followed by
blue-yellow. If it's necessary to use the color combinations
together, make one a dark shade and one a light shade so they
are distinct.

GRAPHICS
High-performance graphics should improve an operator's situational awareness, not be a distraction. While access to an abundance of data is alluring, use it judiciously. The goal is to make
the process easier for operators, not overwhelm them. Fancy or
overly detailed graphics showing every part of a machine can
become clutter and lead to confusion.

SIMPLICITY
Keep it simple. Display only what operators need to know, and
make the data useful. Don't expect operators to know what
a process value means. Instead, show where it is relative to
a good process-value range. Abnormal conditions need to be
obvious. Color must be used sparingly, consistently, and effectively. Consider the number of screens. Adding too many can
hamper operator control. EP

NOVEMBER 2017

http://www.huffmaneng.com http://www.huffmaneng.com/5-tips-hmi-development/ http://www.EFFICIENTPLANTMAG.COM

Table of Contents for the Digital Edition of Efficient Plant November 2017