A Human-Machine Interface (HMI) is a user interface or dashboard that connects a person to a machine, system, or device. It translates complex data into visual information, allowing users to monitor mechanical performance and control industrial processes. Effective HMI implementation replaces manual data recording with real-time digital visualization.
What is Human-Machine Interface (HMI)?
While HMI can technically describe any screen used to interact with a device, the term most often applies to industrial settings. It serves as a communication tool where operators manage machinery via computer monitors, tablets, or built-in screens.
HMIs are not synonymous with Graphical User Interfaces (GUIs). Instead, HMIs often use GUIs to provide visualization capabilities. In a factory setting, an HMI acts as a central console where an operator can check the status of a pump or adjust the temperature of an industrial tank.
Why HMI matters
Industrial organizations use HMIs to optimize operations and reduce human error. Digitizing data eliminates the need for operators to walk the floor and record progress on paper or whiteboards.
- Real-time Visibility: Operators view near real-time information about pressure, vibration, and motor status.
- Centralized Control: Users manage multiple locations and processes through a single console.
- Operational Efficiency: Specific implementations have shown that facilities can [double water treatment capacity while operating with the same number of staff] (AVEVA).
- Resource Management: Modern HMI systems can contribute to a [10 percent reduction in energy consumption] (AVEVA) by optimizing system oversight.
- Issue Diagnosis: Visual charts and alarms help engineers identify and solve problems before they lead to downtime.
How Human-Machine Interface (HMI) works
HMIs function by communicating with Programmable Logic Controllers (PLCs) and input/output sensors. These components gather data from machines and send it to the HMI for visualization.
- Data Acquisition: Sensors on the machinery collect physical data like temperature, speed, or fluid levels.
- Communication: The PLC receives this data and communicates it to the HMI software.
- Visualization: The HMI software transforms the data into graphs, charts, or digital dashboards for the operator.
- Operator Input: The operator provides commands via the HMI (e.g., "turn off pump"), which the software sends back to the PLC to execute.
Types of HMI
The industry uses several interface types depending on the complexity of the task and the hardware required.
| Type | Description | Best Use Case |
|---|---|---|
| Touchscreen | Intuitive screens that replace physical buttons. | Industrial control panels and mobile tablets. |
| Push-button | Centralizes various button functions on one screen. | Simple machine operations. |
| Web-based | Interfaces accessed through standard browsers. | Remote monitoring of automation systems. |
| High-Performance | A design focusing only on critical indicators. | Fast, effective interaction in complex environments. |
| Mobile HMI | Interfaces deployed via apps or mobile-friendly web views. | Remote monitoring and offsite oversight. |
Best practices
Effective HMI design focuses on simplicity and helping operators make fast decisions.
- Use High-Performance design: Clear the screen of extraneous graphics. Only draw attention to critical indicators to help viewers respond to problems efficiently.
- Apply color with discretion: Use color, size, and placement only to highlight important data or alarms. This prevents the operator from becoming overwhelmed.
- Ensure platform agility: Choose HMI software that is platform-agnostic. This allows you to choose the best hardware and networks for your specific needs.
- Implement remote access: Use mobile-friendly interfaces so engineers can confirm system states, such as warehouse temperatures, without being onsite.
- Transition to the Edge: Use Edge-of-network HMIs to access data directly from field devices for faster visualization.
Common mistakes
- Mistake: Overloading the operator with too much information or complex graphics. Fix: Use High-Performance HMI techniques to simplify the display and focus on KPIs.
- Mistake: Using software that only supports specific hardware. Fix: Select future-proof software that supports older operating systems and evolves with new technology.
- Mistake: Failing to integrate HMI with broader systems. Fix: Connect the HMI to SCADA, ERP, or MES systems to centralize all factory data.
- Mistake: Relying on manual data entry alongside the HMI. Fix: Ensure the HMI communicates directly with PLCs to eliminate human error and outdated paper tracking.
HMI vs SCADA
HMI and SCADA are both parts of industrial control systems, but they serve different functions.
| Feature | HMI | SCADA |
|---|---|---|
| Main Goal | Visually convey info for supervision. | System-wide data collection and control. |
| Scope | Limited to a machine or work cell. | Entire plants or multiple sites. |
| Data | Does not typically record data. | Collects and records data in databases. |
| Interaction | Primary communication tool for operators. | The overall control system overseeing HBIs. |
Rule of Thumb: Use HMI for a common-sense view of a specific machine. Use SCADA for the supervisory oversight of the entire enterprise.
FAQ
What is the historical evolution of HMI? Human-machine interaction began with batch processing in the 1950s, where [punch cards were the dominant mode of entering input] (Exor International). In the 1960s, command line interfaces became the [dominant mode of engaging with machines] (Exor International). Later, Graphical User Interfaces (GUIs) introduced the WIMP model (windows, icons, menus, and pointers). Modern HMI has entered a "Post-WIMP" phase involving touchscreens and mobile devices.
What industries use HMI? HMI technology is essential in sectors such as energy, food and beverage, manufacturing, oil and gas, power, recycling, transportation, and water treatment. Almost any organization that manages complex machinery uses an HMI to interact with its processes.
Does an HMI record data? Standard HMIs are focused on visual communication and allowing a user to supervise a process. Unlike SCADA systems, traditional HMIs do not collect and record information or connect to databases. They function as a part of the larger system that may include data recording elsewhere.
Should I make or buy an HMI? Buying a tested solution is generally recommended unless a manufacturer has significant in-house expertise. Building an HMI requires time for design, development, and testing. Purchasing a solution ensures it can keep pace with rapid technological improvements and product renovation.
What is a High-Performance HMI? It is a design method that ensures fast interaction by drawing attention only to necessary indicators. These interfaces are purposely cleared of extraneous graphics. This design helps viewers make better-informed decisions and respond to problems more efficiently.
