The BACnet committee celebrated the approval for final publication of eight addenda to the ANSI/ASHRAE Standard 135, A Data Communication Protocol for Building Automation and Control Networks
at ASHRAE’s recently-held 2010 Winter Conference in Orlando, FL.
The addenda, which include a specification for a standard way of representing data in XML that will give BACnet new capabilities for communications between a wide range of applications, are expected to be available on ASHRAE’s website by the end of this month.
The Extensible Markup Language (XML) is a popular technology in the data processing and communications world due to its capability to model complex data and its flexibility to be transformed and extended. The XML syntax is intended to be the core data representation for a variety of uses, including:
- Powerful new Web services that are capable of efficient exchange of complex structured data.
- An electronic version of a BACnet PICS document, consumable by workstations and other tools, to describe the capabilities of a device.
- An “as built” description of a deployed device, distributed either as a separate file or as a BACnet file object resident in the device itself.
- Descriptions of proprietary objects, properties, and data types, which may be simple, for basic data sharing purposes, or extremely rich, providing complete descriptions of the meaning and usage of the data in multiple human languages.
- An export/import format for tools and workstations to publish their knowledge of a complete system of devices and networks.
- An XML version of an EPICS, including a complete test database and other test-oriented data.
“With this new IT-friendly way of representing building data, BACnet will open up new ways to communicate. XML can be used for exchanging files between systems, communicating with the Smart Grid, and expanding enterprise integration with richer Web services,” says Dave Robin, chair of the BACnet committee.
In addition to XML, another addendum has added an important new capability for human languages as well. The original 2-byte encoding of the Unicode character set caused trouble with a lot of the existing systems that were designed to process only the 1-byte characters common in western languages; the “UTF-8” encoding was created to solve this problem, and quickly became a very popular method of conveying international text on the Internet. BACnet has also embraced this standard and uses it in a way that takes full advantage of it compatibility with the existing and ubiquitous ANSI/ASCII character set.
BACnet has also added support for more data types, including a set of new “Value” objects that rounds out BACnet’s ability to represent different data types in a standard way. New Value objects for every primitive data type that BACnet supports, including support for character strings and large numerics, has been added to the original Analog, Binary, and Multi State Value objects.