Central direct digital control systems are typically used for which type of control?

• A. Open-loop control without feedback.
• B. Local, device-level control only.
• C. Centralize decision making and provide closed-loop control.
• D. Manual control by operators.

Answer: (C)

Central direct digital control systems centralize decision making and provide closed-loop control. A digital processor continuously samples sensors, compares actual conditions to the desired setpoints, and outputs commands to actuators to correct any deviation. That feedback loop is essential for maintaining accurate, stable control even when disturbances occur. Open-loop control has no feedback, local device-level control handles only a single point without coordination, and manual control relies on human input rather than automated feedback. In practice, central DDC coordinates multiple subsystems (like HVAC, lighting, and other building systems) from one controller, enabling automated, coordinated responses to changes.