Direct digital control (DDC) is

• A. A manual switch
• B. Electronic controls used for equipment control and monitoring
• C. A type of mechanical relay
• D. Analog control system

Answer: (B)

Direct digital control uses a digital processor to manage equipment and monitor its operating conditions. In this setup, sensors feed data (like temperature, pressure, or flow) into a controller, which runs software to determine the appropriate outputs. The controller then sends commands to actuators such as valves, dampers, or relays to adjust the system. This approach allows programmable setpoints, scheduling, alarms, and remote monitoring, making it a flexible and centralized way to control and observe equipment. It’s electronic and digitally operated, unlike a manual switch that requires a person to change it, a mechanical relay which is simply a switching device, or an analog control system that relies on continuous signals without digital processing.