What Is The Difference Between HMI And Display?
Key Takeaway
The main difference between an HMI (Human-Machine Interface) and a regular display is that an HMI includes both hardware and software, allowing operators to interact with machines, while a display simply shows information without interaction.
An HMI provides real-time control and monitoring, enabling users to input commands, adjust settings, and view system performance through a graphical interface. On the other hand, a display is a passive component that only outputs visual information, without any control functionality. In short, HMI is a complete system for interaction, while a display is just a screen that shows data.
Definition of HMI
Human-Machine Interface (HMI) refers to a system that allows operators to interact with machines, control processes, and monitor real-time data. The HMI not only displays information but also serves as a control interface, providing an interactive platform for managing equipment. In industrial settings, HMIs are typically designed as touchscreens or control panels that operators use to adjust machine settings, respond to alarms, and monitor performance metrics.
An HMI system communicates with Programmable Logic Controllers (PLCs) or other devices to display data and execute control commands. The purpose of an HMI is to simplify machine operation by offering a user-friendly interface, combining data visualization, control, and feedback mechanisms in one system. For example, in a factory, an operator can use the HMI to change a machine’s settings, view operational data, and control the process—all through one centralized system. The ability to control machines directly from the interface makes HMI a valuable tool in complex industrial environments.
Definition of Display
A display, on the other hand, is a device used to show information visually. Displays are typically limited to outputting data, without offering control functions. In many cases, they are used in conjunction with other systems to provide operators with key performance metrics, alerts, or other operational information. For example, a digital display may show temperature readings or system status but does not allow the user to interact with or control the machine based on that information.
Displays can be found in a variety of forms, such as LED screens, LCD monitors, or numeric readouts. Their primary role is to act as an information output device. Unlike HMI systems, displays are passive and do not provide the same level of interaction or control. In a manufacturing environment, for instance, a display might show the speed of a conveyor belt or the status of a production line, but the operator would need to use a separate system, like an HMI or a control panel, to make adjustments.
Functional Differences Between HMI and Display
The functional differences between HMI and display systems lie in their core purposes. While an HMI system is interactive, allowing operators to control machinery, a display is primarily used to show information. In other words, the display is a part of the HMI system but lacks the interactive elements that define an HMI.
An HMI combines both data display and machine control. For example, an HMI might display operational data such as machine temperature, speed, and pressure, while also allowing the operator to adjust settings or initiate specific functions through a touchscreen interface. The ability to issue commands, set parameters, and respond to alarms makes the HMI a critical component in industrial automation.
By contrast, a display is designed to serve a more limited function—simply presenting information. It lacks the capability to send control signals or adjust operations. For instance, in a power plant, a display might show data such as voltage or current levels but doesn’t allow the operator to adjust these levels. In this way, HMIs provide far more functionality, combining information output with user control, whereas displays are passive tools meant for observation only.
HMI as a Control Interface
One of the key aspects of an HMI is its role as a control interface. Beyond simply displaying data, an HMI allows operators to interact with machinery directly. This interaction can range from starting and stopping equipment to fine-tuning settings for specific processes. For instance, in a chemical plant, an HMI may enable the operator to adjust the flow rate of a chemical mixture, turn on or off pumps, or set alarms for safety thresholds.
HMIs integrate control capabilities with real-time data monitoring, providing operators with immediate feedback on the system’s response to their inputs. This makes it easier to manage complex systems and ensure smooth operations. A key advantage of HMIs as control interfaces is their flexibility—many systems allow operators to customize control layouts, prioritize critical data, and automate repetitive tasks. The interactivity of an HMI makes it indispensable in environments where precise control and real-time feedback are necessary for operational efficiency.
Display as an Information Output Device
Displays, while crucial for presenting information, serve a more passive role compared to HMIs. Their primary function is to provide a visual representation of data or system status without allowing for user interaction. This makes them valuable in scenarios where operators only need to observe system metrics without making adjustments. For example, in a packaging line, a display might show the current number of items processed or the speed of the machine, but it won’t allow the operator to change the speed or settings directly.
Displays are commonly used in conjunction with other control systems. In many cases, operators will view critical data on a display and then use a separate interface, like an HMI or a control panel, to adjust machine operations. While displays are essential for quick and easy data visualization, they lack the depth of interaction that HMI systems offer. Essentially, they are output-only devices, delivering valuable information without providing control functionalities.
Conclusion
In conclusion, both HMIs and displays are essential components in industrial settings, but they serve distinct purposes. An HMI (Human-Machine Interface) offers an interactive platform that not only displays real-time data but also allows operators to control machinery directly. This dual functionality makes HMIs a powerful tool for managing complex operations, where the ability to monitor and adjust processes in real time is critical for efficiency and safety. Operators can use HMIs to make system adjustments, respond to alarms, and interact with various machines all from a centralized location.
On the other hand, a display is a simpler device used exclusively for visual output. It shows critical data such as system status, temperatures, or production rates but lacks the ability to allow user interaction or control. Displays are often used for passive monitoring, providing a clear and concise view of system information. While HMIs are essential for active control and system management, displays serve as a reliable means of presenting data for observation. Understanding when to use each is key to optimizing industrial automation systems.