5 Tips for Designing a Better HMI Screen

September 22, 2023 - Author: Greg Larson, Equipment Project Manager

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An operator using an HMI screen

Recommendations to Improve Your HMI Screen

Human Machine Interface (HMI) screens find extensive use across various industries for controlling processes and equipment. However, the diversity in HMI design approaches appears to be as abundant as the countless viewpoints one can imagine. The question is, what is it that makes for a well-designed HMI screen? The answer is fairly simple. Here are five straightforward tips to ensure the delivery of a clean, professional, and, above all, a valuable and informative HMI application.

#1: Use a Light, Neutral Color for the Background, Preferably Light Grey

Studies consistently indicate that using softer colors such as light grey is easier on the eyes compared to white, black, or flashy colors. Bright colors, when overused, can clash with other elements on the display, making it difficult to read and comprehend the information presented.

#2: Use Color Intelligently

Strategic and purposeful use of color in an HMI can significantly enhance its effectiveness. Colors should be applied with specific meanings, rather than being purely ornamental. For instance, red can be employed to signify alarms or halts, yellow to denote warnings or alerts, and green to indicate operational or safe conditions. Color differentiation is especially beneficial in numeric displays, helping to distinguish between process values and set points, simplifying the identification of editable displays at a quick glance.

#3: Be Consistent When Placing Navigation and Control Buttons on the HMI Screen

Searching for controls because the location changes from screen to screen can be a source of frustration and can lead to inefficient workflows. Whenever possible, place buttons in a consistent order and position at the top of the screens. This HMI design approach not only streamlines the user experience but also improves efficiency in navigation.

#4: Don’t Overload a Screen

Ensure that the most crucial information is prominently displayed on a single screen. For instance, in the context of a chilled water loop, this would encompass essential elements like a basic loop diagram, chiller status, pump status, temperature, and pressure. Secondary parameters such as pump speed or amperage should be positioned on a separate pop-up screen or an alternative location to prevent unnecessary clutter and to maintain the clarity of critical data. The goal is to eliminate the need for users to hunt for vital information, providing them with an efficient and accessible user interface system.

#5: Listen to the Operator when Designing the HMI Screen

This is a tough one, but the operator is the person who will be using this on a day-to-day basis and if you want the project to be truly successful, get his or her input. Although they might not hold decision-making authority, their input is extremely valuable. Operators will often provide feedback to management once the project is delivered, and if they are complaining about the interface, that may impact their willingness to call you for the next opportunity.

While these guidelines are not rigidly fixed, and this list doesn’t cover every possible aspect, following these 5 tips can noticeably elevate the visual appeal and professionalism of your application, leading to long-term client relationships.