Within building automation hardware systems, there is a hierarchical system of micro processor based controllers. Which type of controller is used to provide limited port capacity for connection of…

The system level controller (automation level controller) manages multiple field devices and subsystems, providing supervisory coordination rather than direct sensor connection and standalone DDC execution.

The field level controller (also called a terminal unit controller or application-specific controller) sits at the lowest tier of the BAS hierarchy and is designed to connect directly to sensors and actuators with limited I/O port capacity. It executes DDC programs locally and is engineered to operate in standalone mode, ensuring continued equipment control even if communication with higher-level controllers is lost.

The management level processor handles enterprise functions such as scheduling, trending, alarming, and operator interfaces, operating well above the direct device control layer.

A protocol management system is responsible for translating between different BAS communication protocols and does not directly execute DDC programs or connect to field sensors.

DDC manager is not a recognized tier in the standard three-level BAS hierarchy and does not correspond to a defined controller classification in ASHRAE or industry standards.