BACnet
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BACnet is a Data Communications Protocol for Building Automation and Control Networks. It is an ASHRAE, ANSI, and ISO standard protocol.
The development of the BACnet protocol began in June, 1987, in Nashville, Tennessee, at the inaugural meeting of the Standing 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 eventual became: Interoperability, Efficiency, Low Overhead, Highest Common Multiplier, Compatibility with other applications and networks, Layered ISO Network model, Flexibility, Extensibility, Cost Effective, Transmission Relibility, Apply to real-time processes, Maximum Simplicity, Allow priority schemes, Medium access fairness, and Stability under realistic loads.
The committee worked at reaching consensus using working groups to divide up the task of creating a standard. The working groups focused on specific areas and provide information and recommendations to the main committee. The first three working groups were the Data Type and Attribute Working Group, Primitive Data Format Working Group, and the Application Services Working Group.
BACnet became an ASHRAE/ANSI standard in 1995, and an ISO standard in 2003. BACnet is under continuous maintenance by the ASHRAE Standing Standard Project Committee 135.
The BACnet protocol defines a number of services that are used to communicate between building devices. The protocol services include Who-Is, I-Am, Who-Has, I-Have, which are used for Device and Object discovery. Services such as Read-Property and Write-Property are used for data sharing.
The BACnet protocol defines a number of Objects that are acted upon by the services. The objects include Analog Input, Analog Output, Analog Value, Binary Input, Binary Output, Binary Value, Multi-State Input, Multi-State Output, Calendar, Event-Enrollment, File, Notification-Class, Group, Loop, Program, Schedule, Command, and Device.
The BACnet protocol defines a number of data link / physical layers, including ARCNET, Ethernet, BACnet/IP, Point-To-Point over RS-232, Master-Slave/Token-Passing over RS-485, and LonTalk.
See also
- LonWorks -- A competing protocol and transport medium for BACnet
External References
- BACnet website (http://www.bacnet.org)
- Embed BACnet in your product (http://www.ProtoCessor.com)
- CtrlSpecBuilder - Create HVAC controls specifications (https://www.ctrlspecbuilder.com)de:BACnet