Human-Machine Interface (HMI) in Industrial Networks: Definition, Components, Functions & Examples

Instructor: Erik Rodriguez

Erik has experience working in Cybersecurity and has a Master's of Science in Information Systems.

In this lesson, we will discuss what human-machine interfaces are and the components they are composed of. Additionally, we will review some examples of how human-machine interfaces are used today as well as some of their functions.

Communicating with Machines

''I'll meet you in class,'' you tell your friend as you finish up your research paper. You've worked tirelessly, staring intently at your computer screen as each word you type appears on the screen. The cursor jumps back and forth across the screen as you make changes to your paper. Finally, a quick click of the save and print buttons signals the completion of your work. Everything on the screen, from the cursor to the various menus and buttons, was designed to help you interact with computers to let them know exactly what you want to be done. In like manner, industrial systems utilize human-machine interfaces to allow workers to interact with the various systems, equipment, and sensors used in their everyday jobs.

HMIs allow for humans and machines to interact with one another

HMIs Defined

A human-machine interface (HMI) refers to the various hardware and software components in an industrial system that are tasked with allowing human users and machines to communicate with one another. Similar to how your computer displays menus, graphics, and buttons that allow you to create a research paper, an industrial HMI allows humans to interact with and manipulate things such as valves, sensors, and other components of an industrial system. Additionally, an HMI allows an industrial system to communicate important system information such as metrics, alerts, current functions, and other pertinent system data. To facilitate this exchange, each HMI consists of various components that must work together.

Components of an HMI

The components found in an HMI largely depend on its purpose as well as the industry it is being used in. Generally, though, most HMIs contain some or all of the following components.


Switches are some of the most common components found in HMIs. A switch is used to turn an electrical circuit on or off. Their simplicity makes switches popular choices when designing HMIs that will be used in regulating processes. Additionally, most switches used in industrial HMIs contain a thin membrane underneath the switch that protects the electronic aspect of the switch from debris and moisture. This allows them to operate unimpeded in industrial environments that may otherwise be grueling for electronic devices.

Switches toggle electrical circuits on or off


Keypads consist of a set of buttons which contain alphanumeric characters on them. These buttons allow human workers to input information such as pins, passwords or passcodes, and numerical data into an industrial system. Like industrial switches, keypads used in an industrial setting are sometimes made out of more robust materials that may extend the life of the component. Rubber is sometimes used to make industrial keypads instead of plastic, as it is less likely to break after repeated use.

Industrial keypads are normally made of resilient materials like rubber


Perhaps one of the more important components in an HMI, touchscreens are displays that provide a medium through which humans and machines can exchange information and commands. Without them, humans may find it difficult to input data into the system and the machine will have no way of displaying information to humans. As the name suggests, touchscreens allow humans to interact with aspects of the display by touching the screen with their fingers. This facilitates an easy user experience, as the human operator can physically interact with the information displayed on the screen.

Touchscreens allow humans a way to input instructions for a machine

Functions and Examples of an HMI

As mentioned earlier, HMIs are used in various industries. The functions of an HMI will vary depending on its use. The following are examples of how HMIs may be used in certain industries and what their functions may be.

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