In a modern building automation system, which statement best describes the field controller's scope?

• A. It acts as the primary database for all building data
• B. It runs local control logic, interfaces with local sensors/actuators, and communicates with the BAS
• C. It only displays status on a local screen
• D. It handles only user authentication

Answer: (B)

Field controllers provide real-time, closed-loop control close to the equipment by running local control logic, reading local sensors, commanding actuators, and communicating with the building automation system. This setup lets you react quickly to changes (like temperature or airflow) and keeps the central BAS informed, while the central system handles data storage, analytics, and broader coordination. It’s not just a database or a display-only function, nor is it limited to user authentication. That combination—local control, sensor/actuator interfacing, and BAS communication—best describes the field controller’s scope.