Best Practices
HMI Design Best Practices
A well-designed HMI helps operators run efficiently and respond to problems quickly. A poorly designed HMI creates confusion, errors, and missed alarms. These principles help you design HMIs that work for operators, not against them.
High-Performance HMI Principles
High-performance HMI design, promoted by the ASM Consortium and ISA-101, moves away from the colorful, 3D graphics of traditional HMIs toward functional displays focused on operator effectiveness. The goal is situation awareness — helping operators understand the current state of the process and detect abnormal conditions before they become problems.
Color Philosophy
Reserve color for meaning. In high-performance design, normal operation appears in grayscale — pipes are gray, vessels are gray, values are black. Color appears only when attention is needed: yellow for approaching limits, orange for warnings, red for alarms. This way, color immediately draws the eye to what matters. Avoid decorative color that competes with meaningful indicators.
Information Hierarchy
Design screens in layers. Level 1 provides plant-wide overview — key metrics visible at a glance. Level 2 shows area or unit summaries. Level 3 provides detail screens for individual equipment. Level 4 offers diagnostic and configuration screens. Operators should be able to navigate from overview to detail following the process flow, not hunting through menus.
Alarm Management
Alarm floods are the enemy of effective operations. Every alarm should require operator action — if no action is needed, it's not an alarm, it's a notification. Suppress alarms during startup and known conditions. Use alarm shelving appropriately. Aim for fewer than one alarm per operator per 10 minutes during normal operation. More alarms mean less attention to each.
Traditional vs High-Performance HMI
| Aspect | Traditional HMI | High-Performance HMI |
|---|---|---|
| Color Use | Decorative, realistic | Functional, meaningful only |
| Normal State | Colorful, animated | Grayscale, static |
| Abnormal State | May not stand out | Color draws attention |
| 3D Graphics | Common | Avoided — adds clutter |
| Information Density | Often cluttered | Organized hierarchy |
| Alarm Philosophy | Alarm everything | Alarm only actionable items |
Key Takeaways
Reserve color for meaning — normal operation should be grayscale
Design for the 3AM operator — tired, distracted, possibly responding to an upset
Fewer alarms mean each alarm gets more attention
Navigate by process flow, not menu structure
Test designs with actual operators before deployment
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