Data inside a BACnet device is organized as a series of objects. Each object has a type and a set of properties. There is always at least one object in a device – it is used to represent the device itself . The other objects represent the device’s data.

In practical terms think of a simple thermostat. Our example is a simple device that has a temperature sensor, allows the set point to be changed locally or remotely, has a local remote selection and reports there is an internal fault by reporting its status as normal/abnormal.

Commonly used properties
Object Type:  Popular Object Types: Analog Input, Analog Output, Binary Input, Binary Output.

Instance Number:  A number that must be not be repeated for any other object of the same type.
Name: The optional property called ‘Description’ is usually used to describe the object. This porperty is often no more than a tag.
Present Value: The current value of the object. BACnet has ways of telling you if the present value is valid – it uses a property called ‘Reliability’.