Building automation of high modern buildings or small luxury villas can be seen as a concept work, including hardware and software support for the electric system automation. General structure may be regarded as a three-level unit.
The basic level requires the control combined with physical hardware, such as “Field equipment”, which is electrically controlled and measured. Control elements “Engine Valve” or “Engine damper” are examples of devices that are controlled by an analog signal.
“Temperature Sensor”, “Humidity Sensor”, “Pressure Sensor”, “Light Meter” as well as the field equipment also are examples of analog input signals. The second level includes those elements of the field equipment that transfer the information into electrical signals sent to the “Input-Output Modules”.
Inputs and outputs can be either digital or analog, so the controller divides them into two main groups. Digital signals can be used to express the exact value represented by 0’s and 1’s. For instance, if a “Differential pressure switch” is used to measure whether the air flow in a ventilation duct is, the flow presence is indicated by 1, and its absence is shown by 0. Unlike the static air used for measuring of differential pressure in an air duct, “Differential pressure switch” shows the static pressure difference between two moments of measurement, which is a pascal value.
Accordingly, the analog signals are continuous. When standardized, the “Input-output modules” use different signal types for information exchange with field equipment. Field equipment has individual connections with each device performed by physically separate electric cables. Each module can be used for a single device and there are module models that can be connected to multiple devices. The third level involves a controller. It uses a single communication cable and communication protocol to collect and interpret the information received in a short time cycles from input and output modules. The controller generates outputs as previously programmed.