HMI (HUMAN MACHINE INTERFACE) is a facility in industrial automation using which Human intervention is created in automation process. Based on the communication that the system provides for monitoring, human intervention is made possible for controlling. It provides a graphics-based visualization of an industrial control and monitoring system. Formerly known as MMI (Man Machine Interface), HMI can be installed in an office based Windows computer to communicate with a much specialized computer in the plant area, such as PAC (Programmable Automation Controller), PLC (Programmable Logical Controller) or even DCS (Distributed Control System)
HMI is actually a communicable part of the machine which enables interaction possible between Human and machine. HMI system has Membrane switches, rubber keypads and touch screens to operate. There are some areas of industrial automation where HMI interface is also computerized, which is known as Human-Computer Interface;
While developing HMI, Ergonomics (Human Factors) are considered vitally. Human Factors Engineering (HFE) and Usability Engineering (UE) are essential for developing HMI ideally suitable for any automation system. Graphical representations are more prevalently used for human interface, though other modes are also considered.