The BACnet application services allow access to the objects and provide functions to interact between BACnet applications in a network. Another set of network services on layer 3 of the ISO/OSI model provide routing functions between the different data-link-layers as well as exchanging information about network security.
Application services include object access like reading, writing and change-of-value. Other services provide file-transfer, alarm information, remote device and network management and virtual terminal functions.
To assure interoperability between applications BACnet specifies a PICS (Protocol Implementation Conformance Statement) document. A PICS is a self-declaration by the vendor of a BACnet device and describes which parts of BACnet are supported by the implementation.