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Human Machine Interface

Also known as:HMI

Human Machine Interface: Operator interface through which staff monitor and control an industrial process. The HMI is the window onto operational technologyOperational TechnologyHardware and software used to monitor or control physical equipment, machinery, and industrial processes. — and a preferred target.

How it works and where it fits

An HMI presents plant diagrams, measurements, alarms, and control actions, from a panel at the machine to a full control room. Technically it is often a Windows application or a web interface that speaks industrial protocols to controllers and remote terminal units. Because the HMI holds write access to the process, it is the shortest path between a compromised workstation and a physical effect.

Practical security relevance

Two risks dominate. First, manipulation of the display: falsified readings prevent operators from noticing an attack in progress. Second, reuse of the HMI as a pivot, since it is usually reachable from both the office network and the process network. Hardening means rigorous separation with defined crossings, dedicated accounts with limited rights, patched operating systems, and alerting on unusual switching actions.

  • SCADASCADAControl system for monitoring and operating geographically distributed industrial processes.: Control system for monitoring and operating geographically distributed industrial processes.
  • Operational TechnologyOperational TechnologyHardware and software used to monitor or control physical equipment, machinery, and industrial processes.: Hardware and software used to monitor or control physical equipment, machinery, and industrial processes.
  • Operational Technology SecurityOperational Technology SecurityProtects industrial control, production, and process control systems.: Protects industrial control, production, and process control systems.
  • Programmable Logic ControllerProgrammable Logic ControllerIndustrial computer that cyclically reads sensor values and derives actuator commands for a process.: Industrial computer that cyclically reads sensor values and derives actuator commands for a process.

Related terms