Design HMIs that operators love. Screen layout, alarm design, colour coding, and usability principles for industrial HMI applications in South African manufacturing and mining.
A well-designed HMI can mean the difference between an operator who confidently manages their plant and one who struggles to stay on top of alarms and process upsets. For South African industrial facilities, HMI design directly impacts production efficiency, safety, and operator training time.
HMI Screen Layout Principles
Use a consistent screen hierarchy with navigation that never leaves the operator wondering where they are. Place the most critical information in the upper-left quadrant (the natural starting point for visual scanning). Group related process variables together and use white space to reduce cognitive load.
Colour Coding Standards
Adopt ISA-101 colour standards: green for running/normal, yellow for caution, red for alarm, blue for manual mode, and grey for unavailable data. Avoid using more than four colours on any single screen and never use colour alone to convey critical information — always combine with text labels.
Alarm Management for HMI
Design alarm summaries that show priority, time of occurrence, tag name, description, and current value. Implement first-out indication to help operators identify the root cause of cascade alarms. Provide alarm silencing and shelving with supervisory override for maintenance periods.
Touchscreen HMI Design
For touchscreen HMIs common in South African factories, ensure buttons are at least 40x40 pixels with adequate spacing to prevent accidental presses. Use swipe gestures for navigation where appropriate and provide haptic or visual feedback for all touch interactions.