BACnet
Encyclopedia
BACnet is a communications protocol
for building automation and control networks. It is an ASHRAE, ANSI
, and ISO
standard protocol.
BACnet was designed to allow communication of building automation and control systems for applications such as heating, ventilating, and air-conditioning control, lighting control, access control, and fire detection systems and their associated equipment. The BACnet protocol provides mechanisms for computerized building automation devices to exchange information, regardless of the particular building service they perform.
BACnet became ASHRAE/ANSI Standard 135 in 1995, and ISO 16484-5 in 2003. The Method of Test for Conformance to BACnet was published in 2003 as BSR/ASHRAE Standard 135.1. BACnet is under continuous maintenance by the ASHRAE Standing Standard Project Committee 135.
BACnet had an almost immediate impact on the HVAC
controls industry. In 1996 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. As of May 30, 2011, 515 Vendor IDs have been issued and are distributed internationally. Those vendor identifiers can be viewed at the BACnet website.
H. Michael (Mike) Newman, Manager of the Computer Section of the Utilities and Energy Management Department at Cornell University
, served as the BACnet committee chairman until June, 2000, when he was succeeded by his vice-chair of 13 years, Steven (Steve) Bushby from NIST. During Steve Bushby's four-year term as committee chair the BACnet standard was republished twice, in 2001 and 2004, each time with new capabilities added to the standard. The 2001 version featured, among other things, extensions to support fire / life-safety systems. In June, 2004, 17 years after the first BACnet meeting and back in Nashville, William (Bill) Swan (a.k.a. "BACnet Bill") from Alerton began his four-year stint as committee chair. During his term the number of committee working groups grew to 11, pursuing areas such as support for lighting, access control, energy utility/building integration and wireless communications. In June 2008, in Salt Lake City, Dave Robin from Automated Logic Corporation took over the reins as the new committee chair after serving 4 years as vice chair.
In January 2006 the BACnet Manufacturers Association and the BACnet Interest Group of North America combined their operation in a new organization called BACnet International.
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
.
The general activities of the BTL are:
The BTL also provides testing services through its managed BACnet laboratory. BACnet International and BTL have reached an agreement with SoftDEL Systems
to establish and maintain a test lab for BACnet products. SoftDEL is headquartered in Pune
, India
where the test facility operates BTL. The BTL Manager and BTL working group of BACnet International will administer the test lab. This BACnet lab is ISO 17025 accredited
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
for building automation and control networks. It is an ASHRAE, ANSI
Ansi
Ansi is a village in Kaarma Parish, Saare County, on the island of Saaremaa, Estonia....
, and ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
standard protocol.
BACnet was designed to allow communication of building automation and control systems for applications such as heating, ventilating, and air-conditioning control, lighting control, access control, and fire detection systems and their associated equipment. The BACnet protocol provides mechanisms for computerized building automation devices to exchange information, regardless of the particular building service they perform.
History
The development of the BACnet protocol began in June, 1987, in Nashville, Tennessee, at the inaugural meeting of the Standard Project Committee (SPC). 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 provided 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 ASHRAE/ANSI Standard 135 in 1995, and ISO 16484-5 in 2003. The Method of Test for Conformance to BACnet was published in 2003 as BSR/ASHRAE Standard 135.1. BACnet is under continuous maintenance by the ASHRAE Standing Standard Project Committee 135.
BACnet had an almost immediate impact on the HVAC
HVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...
controls industry. In 1996 Alerton
Alerton
Alerton is a United States company based in Redmond, Washington. Founded in 1981, Alerton is a manufacturer of building automation systems for heating, ventilation and air conditioning HVAC equipment....
announced a complete BACnet product line for HVAC controls, from the operator's workstation down to small VAV controllers. Automated Logic Corporation
Automated Logic Corporation
Automated Logic Corporation is located in Kennesaw, Georgia, and manufactures building automation systems. Several of its technological innovations include: EIKON, a uniquely powerful, universal programming tool; SuperVision, a Graphical User Interface ; ALERT alarm management; Connect...
and Delta Controls soon followed suit. As of May 30, 2011, 515 Vendor IDs have been issued and are distributed internationally. Those vendor identifiers can be viewed at the BACnet website.
H. Michael (Mike) Newman, Manager of the Computer Section of the Utilities and Energy Management Department at Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...
, served as the BACnet committee chairman until June, 2000, when he was succeeded by his vice-chair of 13 years, Steven (Steve) Bushby from NIST. During Steve Bushby's four-year term as committee chair the BACnet standard was republished twice, in 2001 and 2004, each time with new capabilities added to the standard. The 2001 version featured, among other things, extensions to support fire / life-safety systems. In June, 2004, 17 years after the first BACnet meeting and back in Nashville, William (Bill) Swan (a.k.a. "BACnet Bill") from Alerton began his four-year stint as committee chair. During his term the number of committee working groups grew to 11, pursuing areas such as support for lighting, access control, energy utility/building integration and wireless communications. In June 2008, in Salt Lake City, Dave Robin from Automated Logic Corporation took over the reins as the new committee chair after serving 4 years as vice chair.
In January 2006 the BACnet Manufacturers Association and the BACnet Interest Group of North America combined their operation in a new organization called BACnet International.
Protocol Overview
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
ARCNET
ARCNET is a local area network protocol, similar in purpose to Ethernet or Token Ring. ARCNET was the first widely available networking system for microcomputers and became popular in the 1980s for office automation tasks...
, Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
, BACnet/IP, Point-To-Point over RS-232
RS-232
In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...
, Master-Slave/Token-Passing over RS-485, and LonTalk
LonTalk
LonTalk is a protocol optimized for control created by Echelon Corporation for networking devices over media such as twisted pair, powerlines, fiber optics, and RF...
.
BACnet Objects
The standard specifies 50 types of objects| Access Credential | Access Door | Access Point | Access Rights | Access User |
| Access Zone | Accumulator | Analog Input | Analog Output | Analog Value |
| Averaging | Binary Input | Binary Output | Binary Value | Bit String Value |
| Calendar | Character String Value | Command | Credential Data Input | Date Pattern Value |
| Date Value | Date Time Pattern Value | Date Time Value | Device | Event Enrollment |
| Event Log | File | Global Group | Group | Integer Value |
| Large Analog Value | Life Safety Point | Life Safety Zone | Load Control | Loop |
| Multi-state Input | Multi-state Output | Multi-state Value | Network Security | Notification Class |
| Octet String Value | Positive Integer Value | Program | Pulse Converter | Schedule |
| Structured-View | Time Pattern Value | Time Value | Trend Log | Trend Log Multiple |
- Analog Input - Sensor input
- Analog Output - Control output
- Analog Value - Setpoint or other analog control system parameter
- Binary Input - Switch input
- Binary Output - Relay output
- Binary Value - control system parameter
- Calendar - a list of dates, such as holidays or special events, for scheduling.
- Command - Writes multiple values to multiple objects in multiple devices to accomplish a specific purpose, such as day-mode to night-mode, or emergency mode.
- Device - Properties tell what objects and services the device supports, and other device-specific information such as vendor, firmware revision, etc.
- Event Enrollment - Describes an event that might be an error condition (e.g., "Input out of range") or an alarm that other devices to know about. It can directly tell one device or use a Notification Class object to tell multiple devices.
- File - Allows read and write access to data files supported by the device.
- Group - Provides access to multiple properties of multiple objects in a read single operation.
- Multi-state Input - Represents the status of a multiple-state process, such as a refrigerator's On, Off, and Defrost cycles.
- Multi-state Output - Represents the desired state of a multiple-state process (such as It's Time to Cool, It's Cold Enough and it's Time to Defrost).
- Notification Class - Contains a list of devices to be informed if an Event Enrollment object determines that a warning or alarm message needs to be sent.
- Loop - Provides standardized access to a "PID control loopPID controllerA proportional–integral–derivative controller is a generic control loop feedback mechanism widely used in industrial control systems – a PID is the most commonly used feedback controller. A PID controller calculates an "error" value as the difference between a measured process variable and a...
". - Program - Allows a program running in the device to be started, stopped, loaded and unloaded, and reports the present status of the program.
- Schedule - Defines a weekly schedule of operations (performed by writing to specified list of objects with exceptions such as holidays. Can use a Calendar object for the exceptions.
BACnet Testing
BACnet Testing Laboratories was established by BACnet International to test products as per BACnet standard and support compliance testing and interoperability testing activities and consists of BTL Manager and the BTL-WG.The general activities of the BTL are:
- Publish the BTL Implementation Guidelines document
- Certifying the products as per BACnet guidelines
- Support the activities of the BTL-WG,
- Maintaining the BTL test packages for technical support for use of pre-testing
- Approves Testing Laboratories for BTL Testing
The BTL also provides testing services through its managed BACnet laboratory. BACnet International and BTL have reached an agreement with SoftDEL Systems
SoftDEL Systems
SoftDEL partners with industrial product companies for control and connectivity based engineering services. The company focuses on real time, embedded and PC-hosted software development and hardware design to provide product engineering solutions to customers across process and factory automation,...
to establish and maintain a test lab for BACnet products. SoftDEL is headquartered in Pune
Pune
Pune , is the eighth largest metropolis in India, the second largest in the state of Maharashtra after Mumbai, and the largest city in the Western Ghats. Once the centre of power of the Maratha Empire, it is situated 560 metres above sea level on the Deccan plateau at the confluence of the Mula ...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
where the test facility operates BTL. The BTL Manager and BTL working group of BACnet International will administer the test lab. This BACnet lab is ISO 17025 accredited