ATLANTA - The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recently published the newest version of Standard 135-2008, BACnet® - A Data Communication Protocol for Building Automation and Control Networks. The new publication includes seven addenda that add BACnet/Web services and new objects for Event Log, Trend Log Multiple, Load Control, and Access Door. Moving forward, the BACnet committee has 11 addenda in process for the 2008 version.

In addition, addendum q for ASHRAE 135-2008 has been approved for publication and is available in the standards section of www.ashrae.org. Made in cooperation with members of the ZigBee Alliance, the new datalink specification allows mains-powered BACnet devices to communicate over the ZigBee wireless mesh network, opening up new installation options and furthering BACnet’s reach into all areas of facility monitoring and control, according to Dave Robin, BACnet chair.

Robin said the committee is expecting a busy spring public review period, with 11 addenda proposed for standard 135 and four for standard 135.1.

After an extended period to allow for some actual implementations to be prototyped, the BACnet Network Security architecture will go out for its fourth public review as addendum g, bringing state-of-the-art digital signatures and encryption to BACnet, enabling security-critical applications to use a standard protocol.

Developed in collaboration with the Institute of Electrical Installation Engineers, Japan (IEIEJ), the Global Group Object will go out for its second public review in addendum p. This extends the concept of the Group Object to monitor and report on changes in data collected from multiple external devices.

An enhanced Lighting Output Object will begin its third public review in addendum i, and a few additions made to the XML Data Formats will cause it to go out for its second public review in addendum t.

A new set of “Value Objects,” proposed in addendum w, complete the data representation capabilities of BACnet. New objects like String Value Object and Unsigned Value Object enable more opportunities to present data in a standard, rather than proprietary, manner, according to Robin. In addition, the new Time Value Object enables the definition of an extension to BACnet scheduling for non-absolute times, allowing schedules to reference calculated times like sunrise/sunset.

Publication date: 03/16/2009