INTRODUCTION

Think about how you use your phone: the screen shows what’s happening, and you touch the screen to make things happen. In automation, HMIs work the same way—they let people both control a system and understand what it’s doing. You’ve already seen how a PLC can run a process and how buttons can start or stop machines. Now, you’ll explore how HMIs offer more flexible and powerful ways to manage a system.

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WHAT IS AN HMI?

HMI stands for "Human-Machine Interface." Earlier, you learned about how PLCs control and monitor a system. An HMI is a technology that allows humans to interact with a PLC, a machine, and its systems.

HMIs can take various forms, including physical devices like touchscreens, keyboards, and mice, as well as virtual interfaces like software applications. In industrial contexts, an HMI typically refers to a graphical interface (like a screen) that allows operators to monitor and control machinery or processes. This can include displaying real-time data, setting parameters, and receiving alerts or notifications. HMIs are crucial in industries where efficient and intuitive control systems are necessary for operations.

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WHAT AN HMI DOES

An HMI has 2 main roles:

Controlling a system
Displaying data

Controlling A System

In the motor control section, you learned how to use buttons to control the flow of electricity to the conveyor. Many HMIs in industry are set up so that you can use them instead of a start and stop button. They may even have buttons to speed up or slow down a system or to isolate one component (like run just the conveyor or just the robot, instead of the whole system at once). You can also select different functions.

Displaying Data

An HMI can also give an operator information about the machine. It could display speeds, temperatures, product counts, or times. (It all depends on how its programmed and what the company needs.)

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INDUSTRY EXAMPLE

Here is an example of an HMI in industry. This example comes from Gossner Foods in Logan, Utah. It has several different screens, can do different tasks, and displays data.