Interoperability at the management level of building automation systems: A case study for BACnet and OPC UA

In modern building automation systems a plethora of different networking technologies exists. Therefore, interoperability between devices using various technologies is a key requirement. The use of Web Services as a platform-and technological-independent method of communication is a promising approach to address this challenge. Since IP extensions to available technologies are more and more established in building automation systems the network infrastructure and necessary protocols for Web Services communication are already present. However, providing appropriate concepts to model information that can be accessed in a generic way are still missing. OPC Unified Architecture (OPC UA) is a powerful and promising standard that aims at solving this challenge. This work discusses an approach to map the interworking model of BACnet to OPC UA. Using the resulting information model BACnet applications can be represented in OPC UA and, thus, be accessed by OPC UA clients in a standard and well-defined way.