HMIs

A human-machine interface (HMI) is the user interface that connects operators to automated equipment and processes. In industrial automation, HMIs display real-time data from machines, collect operator input, and provide control over equipment and processes.

HMIs come in several forms, including panel-mounted operator terminals with built-in displays, PC-based HMIs that run on standard computers, thin-client or web-based HMIs accessed through browsers, and mobile or remote HMIs for smartphones and tablets.

Common components include a display or touchscreen, input devices such as buttons or touch interfaces, a processing unit, and communication interfaces to programmable logic controllers (PLCs), SCADA systems, or distributed control systems. HMIs support features such as real-time monitoring, alarms, trends, data logging, and recipe or parameter management.

HMIs are designed to work with industrial communication protocols and standards, including OPC UA, Modbus, EtherNet/IP, PROFIBUS, and PROFINET, enabling interoperability with PLCs, sensors, and other devices. Web-based and mobile HMIs enable remote access and centralized monitoring, supporting distributed operations and field work.

The purpose of HMIs is to improve situational awareness, optimize operations, reduce downtime, and enhance safety. Design considerations include reliability, usability, and cybersecurity, as HMIs can be targets for cyber threats; proper authentication, encryption, and secure software updates are essential.