User talk:Funvill/BACnet

For the BACnet article

History
The development of the BACnet protocol began in June, 1987, in Nashville, Tennessee, at the inaugural meeting of the Standard Project Committee (SPC). H. Michael Newman, the first chairman of the committee, presided over the meeting. The first meeting produced a list of 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.

The Development of BACnet
However, LON was still proprietary until 1999 and not fully developed until 1992; thus, prior to that, the buildings industry felt the need to create a standard. Therefore, in 1987, the BACnet Committee was formed within ASHRAE and began to develop a standard that the industry could adopt. It was not an easy goal to achieve a standard that was technically sound, was able to handle buildings data, was truly non-proprietary, and was easy to implement; however, in June 1995, after years of industry input and reviews, ASHRAE adopted BACnet as a new standard for the industry.

Command Contention
All BACnet devices are effectively peers. That means that any device can write the value of an object property in another device. All write commands are sent with a priority and the command with the highest priority is used. If anther write command is sent with a lower priority then the value that is currently being use the write command is ignored.