"HMI" stands for Human Machine Interface. These devices are also referred to as man-machine interfaces (MMIs), operator interface terminals (OITs), local operator interfaces (LOIs), and operator terminals (OTs), but for the purposes of this guide, we will refer to them as HMIs.
HMIs are often used in conjunction with PLCs (Programmable Logic Controllers) to monitor and control processes in an automation system. In general, HMIs allow the user to communicate with the PLC through a graphical interface (usually a touch screen). The interface allows commands to be given and also receives and translates feedback data from the PLC, which is then presented in an easily accessible visualization on the screen. This provides the operator with much needed flexibility and control over a given system. A good example of a common HMI is a tablet or smartphone that has a built-in touchscreen that allows the user to interact directly with the machine's programming.
HMIs generally interact and work on two levels: hardware and software.
At the hardware level, the most commonly used devices for HMIs include monitors, keyboards, mice, touchscreens, scanners, and printers. These devices through a variety of interfaces and cables connected to the computer host and other devices to achieve information input, output and interactive functions. For example, monitors display menus, images, and textual information about the computer system, while keyboards and mice provide convenient and efficient means of input, command, and control between the user and the computer system. Touchscreens, on the other hand, integrate these functions into the same device, and users operate and control them by touching or swiping on the screen.
At the software level, the human-computer interface needs to work to meet user needs through the user operating experience, software interfaces and graphical user interfaces, and to realize communication between the computer and the user through logical control. These software are usually realized by the GUI (Graphical user interface), which realizes the interaction between the user and the computer system through the operating system and application management.
GUI mainly contains a variety of interface elements such as forms, menus, buttons, dialog boxes, toolbars, status bars, prompt messages and help files. The design of these interface elements and interactions needs to take into account the user experience and functionality and other aspects to meet the user's needs and operating habits.
In general, the human-computer interface realizes the functions of information input, output, interaction and control between human and computer system at both hardware and software levels, providing users with convenient, efficient and intuitive operation experience, which is crucial for enhancing the usability and popularization of computer system.