HMI screen layout principles in SCADA systems - Full Explanation

Introduction

Imagine trying to control a complex machine but the control screen is confusing and cluttered. This makes it hard to find important information quickly and can lead to mistakes. Good HMI screen layout principles help organize information clearly so operators can work safely and efficiently.

Explanation

Clarity and Simplicity

The screen should show only the most important information needed at a glance. Avoid clutter by limiting colors, shapes, and text. Clear labels and simple graphics help operators understand the system quickly without confusion.

Keep the screen simple and clear to help users find key information fast.

Consistency

Use the same colors, fonts, and symbols throughout all screens. Consistent layout and behavior reduce the learning curve and prevent errors by making the interface predictable.

Consistent design helps users feel familiar and confident with the system.

Logical Grouping

Group related controls and information together based on function or process flow. This helps operators understand relationships and navigate the screen naturally.

Organize elements logically to match how the process works.

Prioritization and Hierarchy

Important information like alarms or critical values should stand out using size, color, or position. Less important details can be smaller or placed in secondary areas. This guides attention to what matters most.

Highlight critical information so it catches the operator’s eye immediately.

Feedback and Visibility

The screen should clearly show the current status of the system and respond visibly to operator actions. This feedback confirms commands were received and helps detect problems early.

Provide clear feedback so users know what is happening at all times.

Real World Analogy

Think of a car dashboard where the speedometer, fuel gauge, and warning lights are arranged so drivers can quickly see important details without distraction. If the dashboard was cluttered or inconsistent, driving safely would be harder.

Clarity and Simplicity → A clean dashboard showing only essential gauges and indicators

Consistency → All dashboard lights and symbols using the same style and colors every time

Logical Grouping → Grouping speed, fuel, and engine info in separate areas on the dashboard

Prioritization and Hierarchy → Warning lights that glow bright red to grab attention immediately

Feedback and Visibility → Dashboard lights turning on or off to show system status changes

Diagram

Diagram

┌───────────────────────────────┐
│          HMI Screen           │
├─────────────┬─────────────────┤
│ Critical    │ Secondary Info  │
│ Alarms      │ and Controls    │
│ (Bright,    │ (Smaller,       │
│ Top-Left)   │ Bottom-Right)   │
├─────────────┴─────────────────┤
│ Logical Grouping of Controls   │
│ (Grouped by Function)          │
├───────────────────────────────┤
│ Consistent Colors & Symbols    │
│ Simple, Clear Labels           │
└───────────────────────────────┘

This diagram shows an HMI screen layout with critical alarms prioritized at the top-left, secondary info grouped logically, and consistent design elements.

Key Facts

Clarity → Only essential information is shown clearly to avoid confusion.

Consistency → Design elements like colors and symbols remain uniform across screens.

Logical Grouping → Related controls and data are placed together based on function.

Prioritization → Critical information is visually emphasized to attract attention.

Feedback → The system visibly responds to user actions and status changes.

Common Confusions

More information on screen means better control.

More information on screen means better control. Too much information causes clutter and slows decision-making; simplicity improves safety and speed.

Using many colors makes the screen easier to understand.

Using many colors makes the screen easier to understand. Excessive colors can confuse users; limited, meaningful colors improve clarity.

Grouping controls randomly is fine as long as they fit on the screen.

Grouping controls randomly is fine as long as they fit on the screen. Controls must be grouped logically by function to help users find and use them efficiently.

Summary

Good HMI screen layouts keep information clear and simple to help operators act quickly.

Consistent design and logical grouping reduce errors and make the system easier to learn.

Critical information must stand out visually to guide operator attention effectively.