After building two user interfaces this year and having to formulate and review the rules for developing an effective set of screens each time, this is a list of seven items created from experience, client feedback and research.
7 HMI Design Guidelines
1. Do not use black or white for background. It appears that this would bring about good contrast and highlight objects onscreen but to the contrary, it succumbs to glare in many lighting conditions including sunlight and fluorescent lighting.
2. Low contrast general themes are better in industrial user interfaces for the following reasons: 1- It helps highlight situations that require awareness, 2- It’s not too eye catching as an industrial control system should be. Captivating graphics may steal from the actual intent.
3. Use graphs and trend information where possible. Visual aspects of monitored variables allowsfor easier troubleshooting. Historic view of what the variable has done whether a few minutes ago or a few hours ago helps operators with decision making. A trend can also captures a relative view of the current state with respect to limits and also in relation to other variables.
4. Articulate situations that are beyond acceptable or normal operating regions using bar graphs and colors( red, yellow green). This supports the notion of providing a relative view of the status of a process variable or condition.
5. Do not use too many elements that do not carry data significance. Example: An elaborate drawing of a plant or process with only 4 or 5 actual data fields may serve as a distraction. The idea is not to amaze users/operators/viewers with the graphics but to provide information and allow for efficient and optimal control.
6. Consider replacing color based information with shapes- helps with color blindness and confusion on the meaning of colors. Example: Does RED infer push to stop or currently stopped. Does green mean go or push to go?
7. Spacing between user input fields- avoid the proverbial ‘fat finger’. Example :Placing two input fields together can cause errors in data entry. Consider placing a label between input fields.
