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.

Practice

1. What is the main purpose of grouping related items together on an HMI screen?

easy

A. To make the screen look more complex

B. To make the screen easier to understand and use

C. To increase the number of buttons

D. To use more colors on the screen

Solution

1. Step 1: Understand grouping concept

   Grouping related items helps users find information quickly and reduces confusion.

2. Step 2: Consider user experience

   A clear layout improves safety and efficiency by making controls intuitive.

3. Final Answer:

   To make the screen easier to understand and use -> Option B

4. Quick Check:

   Grouping = Easier use [OK]

Hint: Group related controls for clarity and ease [OK]

Common Mistakes:

• Thinking more colors always improve clarity
• Adding too many buttons without grouping
• Ignoring user navigation needs

2. Which of the following is the correct way to label buttons on an HMI screen?

easy

A. Use clear, descriptive text like 'Start Pump 1'

B. Use vague terms like 'Start' without context

C. Use only icons without any text

D. Use random colors without meaning

Solution

1. Step 1: Identify labeling best practice

   Clear, descriptive labels help users understand button functions immediately.

2. Step 2: Avoid vague or confusing labels

   Labels like 'Start Pump 1' are better than generic or icon-only labels for clarity.

3. Final Answer:

   Use clear, descriptive text like 'Start Pump 1' -> Option A

4. Quick Check:

   Clear labels = Better understanding [OK]

Hint: Use clear text labels, not vague or icon-only [OK]

Common Mistakes:

• Using unclear or generic button names
• Relying only on icons without text
• Ignoring color meaning in labels

3. Consider this HMI screen layout code snippet:

screen = {
  'title': 'Main Panel',
  'buttons': [
    {'label': 'Start', 'color': 'green'},
    {'label': 'Stop', 'color': 'red'},
    {'label': 'Reset', 'color': 'yellow'}
  ]
}

What is the main issue with this layout?

medium

A. Button colors do not match their typical meanings

B. Button labels are too descriptive

C. The screen title is missing

D. There are too many buttons

Solution

1. Step 1: Analyze button colors and meanings

   Green for 'Start' matches (go/action), red for 'Stop' matches (danger/stop), but yellow for 'Reset' does not--yellow typically means caution/warning, not reset.

2. Step 2: Confirm other options

   Labels are simple (not too descriptive), title present, few buttons--issue is color mismatch.

3. Final Answer:

   Button colors do not match their typical meanings -> Option A

4. Quick Check:

   Colors should match meaning [OK]

Hint: Match button colors to their common meanings [OK]

Common Mistakes:

• Ignoring color conventions
• Assuming more buttons are always bad
• Overlooking screen title presence

4. You notice an HMI screen is cluttered with many controls and colors. What is the best way to fix this?

medium

A. Remove all labels to save space

B. Add more colors to differentiate controls

C. Group related controls and reduce color usage

D. Increase screen brightness

Solution

1. Step 1: Identify clutter causes

   Too many controls and colors make the screen confusing and hard to use.

2. Step 2: Apply layout principles

   Grouping related controls and limiting colors improves clarity and usability.

3. Final Answer:

   Group related controls and reduce color usage -> Option C

4. Quick Check:

   Less clutter = Better usability [OK]

Hint: Group controls and limit colors to reduce clutter [OK]

Common Mistakes:

• Adding more colors increases confusion
• Removing labels reduces clarity
• Changing brightness does not fix layout

5. You need to design an HMI screen for a complex system with many controls. Which approach best follows good layout principles?

hard

A. Use flashing colors to attract attention to all controls

B. Put all controls on one screen with random colors for each

C. Use only icons without labels to save space

D. Create multiple screens grouping related controls and use consistent colors

Solution

1. Step 1: Understand complexity management

   Complex systems require breaking down controls into manageable groups to avoid overwhelming users.

2. Step 2: Apply layout best practices

   Using multiple screens with grouped controls and consistent colors improves navigation and safety.

3. Step 3: Avoid poor practices

   Random colors, icon-only labels, and flashing colors cause confusion and reduce usability.

4. Final Answer:

   Create multiple screens grouping related controls and use consistent colors -> Option D

5. Quick Check:

   Group + consistent colors = Best design [OK]

Hint: Use multiple grouped screens with consistent colors [OK]

Common Mistakes:

• Trying to fit all controls on one screen
• Using random or flashing colors
• Relying only on icons without text