Which of these control systems is used to monitor and control equipment via computers and data communication?

The correct choice is SCADA, which stands for Supervisory Control and Data Acquisition. SCADA systems are specifically designed to monitor and control industrial processes, infrastructure, and facility-based operations. They utilize data communication to gather real-time information from various sensors and devices distributed across a geographic area, often integrating with computers to analyze this data and facilitate decision-making.

SCADA systems allow operators to control equipment from a central location, providing visualization of systems through graphical interfaces, alarms for abnormal conditions, and the ability to execute commands remotely. They are extensively used in utilities, manufacturing, transportation, and building management, demonstrating their crucial role in modern industrial operations.

While PLC (Programmable Logic Controller) is also an important component in automation that may control machinery directly, it does not inherently provide the broad monitoring and data aggregation capabilities that SCADA offers. RTUs (Remote Terminal Units) serve to collect data from field devices and relay it back to a central system, often functioning as a part of a SCADA setup rather than as standalone systems. HMIs (Human-Machine Interfaces) are used for interfacing with and controlling machines but do not encompass the comprehensive monitoring and control functions provided by SCADA systems.