A human-machine interface (HMI) is a device that allows humans to give instructions and receive feedback from a PLC that controls a manufacturing process. In other words, it is a user interface or dashboard that connects a person to a machine, system, or device. While technically the term can be applied to any screen that allows a user to interact with a device, HMIs are most commonly used in industrial processes.
HMIs can take many forms, including a graphical user interface (GUI) on a computer, a touchscreen, or a physical control panel with buttons and a display. They are used to provide process data to operators, allow operators to enter commands and setpoints, and display alarms and other information.
HMIs are typically connected to a programmable logic controller (PLC), which is responsible for controlling the process based on input from the HMI and field sensors. The HMI simply provides information to operators and allows them to enter commands, which are then sent to the PLC for implementation.
