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Once factory automation reaches a certain level of complexity, it may be useful to introduce an HMI organization concept of levels such as:
• Level 1 Dashboards: Provide summary “at a glance” operating information
• Level 2 Typical Control: Streamlined
operating screens, provide the essential
monitoring and control options
• Level 3 Detailed Control: Detailed
operating screens, with more options
than Level 2
• Level 4 Specific Control: Very detailed
popup, configuration, or diagnostics screens, not regularly used
During the story boarding process, keep
in mind that team members include not just programmers, but also those from other engineering disciplines, along with operators, maintenance members, and management. Each member will contribute corresponding to their role.
Define the Style
The style for an HMI encompasses many look, feel, and functionality aspects. While current “high performance” HMI concepts call for minimized colors and very simple objects, each user must adopt what is suitable for their specific application (Figure 3). Here are some considerations for creating an HMI style guide.
Figure 3: Image of a configured HMI in use. Developing and following an HMI style guide will allow designers to configure intuitive HMI screens which operators can easily navigate to monitor and control factory automation systems.
Cover Story
Navigation and Availability
Common sense indicates that the most important controls, typically start and stop commands as well as navigation buttons, should always be easily available. A common way to do this is by reserving a portion of every screen for
these controls.
Pop-ups are smaller windowed screens appearing in front of a full-display screen, usually used briefly for viewing and/or entering very specific information and then dismissed. Sometimes it is helpful to allow a pop-up to persist, such as for a PID tuning faceplate. However, while pop-ups may be useful for infrequent detailed tasks they can be a distraction for normal operation, consume space on the display, and should often be avoided.
Password protection security should be applied as needed, but judiciously to avoid locking down a system and impeding operators. It is often useful to consolidate machine tuning parameters on a single password-protected screen.
Be Careful with Color
Colors are used for backgrounds, fonts, static elements, and animated objects, but they can be
a debated HMI topic. Most standards recommend light grey backgrounds and greyscale objects, with colors reserved for abnormalities. This provides
easy visibility and guides users to what is import-
ant. However, an industry or equipment may dictate the use of color. Power industries often use red for energized (danger) and green for de-energized (safe). If an item of equipment has three color-coded subsystems, perhaps it makes sense to include those colors on the title bar for easy recognition.
Another point is to avoid relying only on animated color-coding of objects. Where possible, it is better to provide a secondary supplementary symbol indication of a state or condition.
Defining Text Data
Style also extends into what fonts are used and how text is capitalized. Plan on defining just a few fonts to cover the necessary scenarios. Reserve larger/bolder versions for titles and important things, and smaller types for details. Make it clear which values are display-only, and what can be
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Editor's Note
New Product Focus
- Expaded communications and analog I/O capabilities for the
- Control cabinet cable entry systems
- DURApulse® GS20 Series high performance AC drives
- ProSense® Advanced Process Conrollers
- Enclosure Thermoelectric Coolers
Tech Thread
Improvies, Adapt, Overcome
Business Notes
Cover Story
The Best Automation HMIs Keep Things Simple
What's New
User Solutions
- Water Utility Successfully Standardizes Automation Practices
- Automating the Hendrick's Gin Grand Garnisher
Student Spotlight
CPAPs RE-INVENT ed into Ventilators Using PLCs & HMIs
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 Brain Teasers | Issue 44

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