A human-machine interface (HMI) is the hardware or software that lets a person interact with a machine, device, or controller. In industrial automation, it can be a physical panel with buttons and indicator lights, a computer display running HMI software, or a combination of controls and displays. The interface is how an operator communicates with a system; it is not necessarily the system’s underlying controller or automation logic.
What does HMI mean?
HMI stands for human-machine interface. NIST’s glossary defines it as “the hardware or software through which an operator interacts with a controller.” Its examples range from a physical control panel to an industrial PC with a color graphics display running dedicated HMI software. The definition appears in the NIST CSRC glossary, which cites NIST SP 800-82 Rev. 3.
The phrase is not limited to industrial control rooms. ISO’s online glossary gives a broader formulation: “controls and displays that allow a human to interact with a manufactured device or system,” citing ISO/TR 12204:2012. That definition covers interaction with manufactured devices and systems generally, not only industrial controllers. See the ISO Online Browsing Platform glossary.
What can an HMI look like?
An HMI may be simple or sophisticated, and it does not have to be touchscreen-based. Examples include:
- A physical control panel: buttons and indicator lights provide input and show status.
- A computer-based interface: an industrial PC displays information and accepts operator input through dedicated HMI software.
- A combination: physical controls and electronic displays work together to support interaction with a device or process.
These forms are examples, not a universal product checklist. The suitable interface depends on what is being controlled and how people need to interact with it.
How is an HMI different from a controller?
The HMI is the operator-facing means of interaction; the controller is the system a person interacts with. An HMI may let an operator view information or provide input, but the glossary definitions do not make the interface itself responsible for executing the controller’s underlying automation logic. Treating the display or panel and the controller as the same thing can blur an important distinction between operating a system and the system’s control functions.
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- 7 Inch HMI GL070 GL070E Human Machine Interface Control Display Screen
What does HMI mean in industrial automation?
In process automation, an HMI is part of the connection between an operator, a control system, and the process being controlled. The International Electrotechnical Commission’s IEC 63303:2024, Human machine interfaces for process automation systems, addresses HMI structures and functions as well as lifecycle requirements and recommendations for designing, using, and maintaining these systems. IEC lists it as a first edition published on 2024-08-06. Its scope is process automation where an HMI interfaces with a control system; implementation can vary with the application and type of controlled process. See the IEC publication page.
What goes into designing an industrial HMI?
Industrial HMI design involves more than choosing a screen or panel. ISA’s ISA101 committee develops standards, recommended practices, and technical reports for HMIs in manufacturing applications. Its stated design topics include:
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- Premium Design: The HMI adopts 32 bit 240MHz ARM9 and 128M NAND FLASH memory with a download speed of 38.4KB, mainly used for various PLCs or intelligent controllers with communication ports, compatible with FX3U‑20/40/48MRT.
- Clear in Display: 7in TFT LCD screen with 800 x 480px resolution, 400cd/m² brightness with backlight display, easy to observe.
- The is equipped with an ARM9 processor, resulting in high touch accuracy. The front panel complies with lP65 flat panel installation, and the rear shell of the body complies with IP20.
- Wide Application: This is a small human machine interface mainly used for various PLCs or intelligent controllers with communication ports. has low power consumption, fast speed, and
- Easy Installation: The opening size is 190mm x 136mm, equipped with screws and fixing accessories, can be installed directly.
- Screen navigation and organization
- Graphics, color conventions, and dynamic elements
- Alarm handling
- Security methods
- Interfaces with programming and historical databases
- Popups, help screens, and configuration interfaces
These topics are practical design concerns, not a claim that every interface uses the same layout or features. The ISA101 committee outlines its scope on its committee page.
Why do HMI standards cover a lifecycle?
An interface has to be designed and implemented, then used, maintained, and improved as the system and its operating needs evolve. ISA’s series page describes ANSI/ISA-101.01-2015, Human Machine Interfaces for Process Automation Systems, as covering design, implementation, operation, and continuous improvement. It also lists supporting material, including ISA-TR101.01-2022, HMI Philosophy. Availability and current editions can change; consult the ISA-101 series page for current listings.
Usability and performance are also explicit concerns. ANSI Webstore describes ISA TR101.02-2019, HMI Usability and Performance, as guidance covering specification, design, implementation, and management, and the application of ISA-101.01-2015. See the ANSI Webstore listing.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How should you think about HMI options?
There is no universal best HMI form established by the standards summaries. When assessing an interface for a particular use, relate it to the work it must support:
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- 7 Inch HMI GL070 GL070E Human Machine Interface Control Display Screen
- Whether operators need physical controls, display-based interaction, or both
- The process and application being controlled
- How information, navigation, and alarms are presented
- Usability, security, and integration with programming or historical data
- How the interface will be implemented, operated, maintained, and supported over time
Those considerations follow the kinds of concerns covered by ISA and IEC materials; they are not a standardized scoring formula. The right design depends on its operating context.
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