Human Machine Interface (HMI) in industrial context are screens that connect users to machines, instruments and operations. Operators uses HMI to visualize information to assist them in supervising and controlling.
HMI is often integrated with SCADA (Supervisory Control and Data Acquisition) system; collecting data from RTU (Remote Terminal Units), PLC (Programmable Logic Controllers), I/O sensors and other field instrumentation such as flowmeter, water analyzers, level sensors, pressure and temperature sensors, pumps, actuators, etc. HMI allows the users to monitor the pre-defined parameters in real time, from a centralized location.
Wastewater treatment facility for example, involves multiple stages and can take place in areas that expand across a few kilometers. An HMI display at a centralised control room can ease the operators’ daily task in monitoring processes. Water quality parameters include chemical, physical, and biological properties and can be measured and monitored based on the desired water parameters of concern. Parameters that are frequently sampled or monitored for water quality include temperature, dissolved oxygen, pH, conductivity, ORP, and turbidity. It may also include measuring total algae, ammonia, nitrate, chloride, or laboratory parameters such as BOD and TOC.
Best Practice for an Effective HMI Design
- Screen size: Select a screen size that is appropriate and represent the process, without being too cluttered or with unwanted empty space.
- Easy to comprehend: Live process values and instrument labels needs to be prominent and easy to read. Data should be displayed in a manner that mimic the actual workflow on-site. Graphical screen should be used in a manner to only show important process not able to show by labels or tags, without being too flashy. Flashy screens have the tendency to drown out actual important data or alarm that should be highlighted.
- Avoid overloading: Each display page should be kept clear and uncluttered to enhance readability. Do not saturate the screen with overload of 3D models and animations, as it could potentially distract or delay observation of a critical data. Not all data are important and need to be shown. Secondary data for troubleshooting can be stored in a separate diagnosis screen without cluttering the usual process screen.
- Logical navigation: HMI is a collection of screens. Important screens such as the “Overview” and “Alarm Summary” should be a click away. Draft a workflow mapping and group screens in a logical hierarchical order, to make it easy to navigate, even for non-technical users. Screens should not take more than 2 clicks to reach important pages.
- Colour: Some users maybe colour blind; therefore, colour change for alarm or hazard situations is not sufficient. A flashing border, additional symbol or audible notification (with siren device) is advised to be added for easy identification.
There is no one-size-fits-all solution in industrial HMI design. An effective HMI design can provide visual displays that is easy to understand and interact with.
Contact us to explore about HMI design and developing an adaptable, practical solution to monitor and manage operation process with higher productivity and safer operations, ultimately leading to an increased ROI.
