General building automation network structure is shown on the drawing below. Of course, number and types of the devices would be different in each installation, depending on its size and designation.

In general, control systems consist of the following device groups:


Sensors are devices converting environmental parameters into numbers, or external actions into system events. Temperature and humidity meter is a sensor, wall switch or open door detector is a sensor.


These devices allow the system to interact with the environment. They could be used to open and close a roof window, or for light dimming.

Sensor and actuator function can be combined into a single device. On the drawing below you can see an example configuration of Extendable BACnet Device, which combines relay outputs, switch inputs, light dimmer and energy consumption meter into single unit.

System controller

System controller (or sometimes called Building Controller) is the device which reacts to data from sensors by controlling actuators. It can use data from multiple sensors to take proper decision, for example pressing a button will close a gate only when the infrared sensor does not detect anybody around.

Small systems can be controlled by single controller based on 32-bit CPU, installed in the electrical installation box.
Bigger installations mean increased number of events to handle, and stricter requirements regarding fault tollerance. Such controllers could consist of several high-end servers connected by Gigabit Ethernet network with redundant power supplies. UPS is a must.

Operator console

This is the place where the user can manually control the system and view values provided by sensors. Un user mode the information is shown and interaction is performed via predefined, user-friendly screens. There is also an expert mode, where all system figures are shown in table style

Supporting devices

Normally invisible to a user, these devices provide low voltage supply and connectivity to the network

About ReasonableControls

ReasonableControls company is a dynamic team of people who decided to be creative on their own. With strong technical background and years of experience in embedded systems design, want to give you the advantages of automation systems without using magic words, for reasonable price.


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