Control System
A control system is a system of hardware and software that regulates the operation of a device or group of devices. In the case of building management systems, the controlled devices are usually HVAC (heating, ventilation, and air conditioning) systems, but can also include lighting, security, and other building functions.
The purpose of a control system is to maintain a desired condition in the controlled system, such as keeping the temperature at a comfortable level. Control systems use feedback loops to compare the actual condition with the desired condition and make adjustments as needed to maintain the desired condition.
There are many different types of control systems, but all share some common elements. These common elements include sensors to measure the actual condition, actuators to change the controlled condition, a controller to compare the actual and desired conditions and make adjustments, and communication infrastructure to connect the various components of the system.