Download Architecture Specification

AIM
Deliverable D2.2
desirable attributes of a good protocol, and what the BACnet protocol eventually became:
Interoperability, Efficiency, Low Overhead, Highest Common Multiplier, Compatibility with other
applications and networks, Layered OSI model Network, Flexibility, Extensibility, Cost Effective,
Transmission Reliability, Apply to real-time processes, Maximum Simplicity, Allow priority
schemes, Medium access fairness, and Stability under realistic loads.
BACnet had an almost immediate impact on the HVAC controls industry, which by 1996 was
dominated by Siemens Building Technologies. Although several manufacturers had developed
BACnet devices, in 1996 a smaller company, Alerton, announced a complete BACnet product line for
HVAC controls, from the operator's workstation down to small VAV controllers. Automated Logic
Corporation and Delta Controls soon followed suit. Other current examples of suppliers offering full
lines of BACnet building automation products are Siemens Building Technologies, Johnson Controls,
Inc., Teletrol Systems, TAC, KMC Controls, Contemporary Controls Ltd, Reliable Controls and
PRIVA. Carrier has plans to transition completely over to BACnet in the next few product cycles.
BACnet is an entirely non-proprietary system. This means that there are no proprietary chip sets or
protocols used. Information regarding the comparison of BACnet and LonWorks (a protocol
technology often compared to BACnet) is contained in an online white paper from BACnet
International (1996) and an online white paper from Strata Resource Inc.(2006).
6.1.8.2
The Development of BACnet
For many years, as building automation systems became popular, more and more users were
demanding alternatives to proprietary systems, which prevented competitive bidding or serviceability.
They objected to being "locked in" to one particular manufacturer. A consensus and industry attitude
has been developing to respond to this need.
Most solutions providing interoperability are proprietary gateways or converters. For instance, one
particular manufacturer may have found a way to read the code of another manufacturer and produce
a device that lets the two systems communicate. Sometimes the development is a cooperative effort;
other times it is not. The end result, however, is that one manufacturer could provide either a new or
different operator's terminal or global controller for a different manufacturer's existing system.
There were other control-network protocols in existence before -- and coinciding with -- the
development of BACnet but they didn’t meet all of the desired criteria at the time: primarily, that the
standard had to be technically sound, be able to handle buildings data, be truly non-proprietary, and be
easy to implement.
© AIM consortium 2008/2009/2010
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