HMI Screen Design Techniques: Five Key Principles for Operator Efficiency

1. Introduction — HMI Determines Operator Efficiency

In industrial automation, the HMI (Human-Machine Interface) acts as the operator’s window into the machine.
Even the best PLC logic cannot compensate for:

Poor interface layout
Confusing buttons
Bad color usage
Overcrowded pages

A well-designed HMI significantly improves:

Operator speed
Troubleshooting efficiency
Machine uptime
Safety

This guide explains the five core principles of effective industrial HMI design.

2. HMI Layout Principles

2.1 Block-Based Layout

Divide the HMI into sections:

Machine status
Main controls
Alarms
Parameter settings
Navigation

Block-based design prevents visual clutter.

2.2 Consistency Across All Screens

Consistency improves user learning and reaction time:

Font sizes
Color standards
Button positions
Icon usage
Navigation structure

Operators should instantly understand any new page without training.

2.3 Prioritize Main Machine Process

Place key controls in high-visibility areas:

Cycle start / stop
Alarm reset
Key parameters
Real-time values

Important elements should appear above the fold and centered.

3. Control Element Design

3.1 Indicators: Numbers, Status Lights, Alarms

Use clear visual rules:

Green → Running
Red → Fault
Yellow → Warning
Blue → Info

Numeric displays require:

Clear font
Adequate spacing
Meaningful units

3.2 Button Layout

Buttons must follow:

Logical position → relevant to the action
Visual grouping → similar actions grouped
Left to right, top to bottom for user flow
Sufficient size for gloved hands

3.3 UI Style (Colors, Fonts, Spacing)

Good industrial HMI design avoids:

Excessive gradients
Overly saturated colors
Decorative fonts
Tight spacing

Use neutral backgrounds + accent colors for important actions.

4. Page Logic and Navigation Flow

4.1 Recommended Page Structure

Typical industrial HMI pages:

Main Screen
Parameter Settings
Alarm Page
Manual / Jog Controls
System Configuration

4.2 Input Verification & Permission Control

Critical actions must include:

Confirmation dialogs
Password protection
Role-based access (Operator / Technician / Admin)

Improper input validation is a major cause of runtime faults.

5. Engineering Use Case Examples

5.1 Packaging Machine UI

Features:

Real-time counter
Conveyor status
Temperature zones
Alarm summary

5.2 CNC Machine Status Screen

Displays:

Spindle speed
Feed rate
Tool number
Axis position
Alarm conditions

5.3 Pneumatic System Control Interface

Includes:

Cylinder status
Valve control
Sensor feedback
Pressure indicators

6. Common HMI Design Mistakes

❌ Information density too high

Operators cannot quickly locate controls.

❌ Poor color discipline

Overuse of bold colors reduces clarity.

❌ Buttons too small

Hard to press with gloves or in fast situations.

7. Best Practices for Reliable HMI Design

✔ Use a unified color strategy

Green/Red/Yellow/Blue across all screens.

✔ Provide historical data & trends

Important for troubleshooting.

✔ Structured alarm & log management

Essential for fast maintenance response.

HMI Screen Design Techniques: Five Key Principles for Better Operator Efficiency