ANSI/ASHRAE Standard 135-1995, “BACnet – A Data Communication Protocol for Building Automation and Control Networks,” is the only open, consensus-developed standard in the building controls industry.
Proposed addendum d replaces the Conformance Class and Functional Group structure of the current standard with a new approach based on BACnet Interoperability Building Blocks (BIBBs). The BIBBs are grouped into five “interoperability areas” – data sharing, alarm and event management, scheduling, trending, and device and network management. Each BIBB defines the communications requirements for achieving a particular interoperability goal. BIBBs come in pairs that match the client-server used in BACnet.
“This new approach eases the burden on owners and consulting engineers who do not understand the details of digital communications,” Steven Buchby, committee chair, said. “Today, many of them have difficulty writing a clear BACnet specification. This new approach allows them to select the areas of interoperability that are important for the project and reference the BIBBs that apply to those interoperability areas.”
The addendum includes an informative annex that defines the BIBBs required for a particular set of control devices. These devices are a BACnet workstation, BACnet building controller, BACnet advanced application controller, BACnet application specific controller, BACnet smart actuator, and a BACnet smart sensor.
Also proposed is addendum e, which contains three unrelated additions to BACnet. The most significant is a standard method for describing extensions to standard objects and also new object created to map BACnet to other proposals.
The addenda opened for public review on Dec. 1 and will close January 30, 2001.