Introduction to BACnet Presented by Jianqing Zhang.

Introduction to BACnet

Presented by Jianqing Zhang

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Overview

• BACnet: Building Automation and Control Networks

• Supported by SPC of ASHRAE since 1987– Standard Project Committee (SPC) 135P – American Society of Heating, Refrigerating an

d Air-Conditioning Engineers

• Position:– American national standard– European pre-standard– ISO global standard

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Benefits of BACnet

• Single point of control• Competitive system expansion• Eliminate fear of being “locked in”• Possibility of integrating all BAC functions• Low cost• Interoperability

– Data sharing– Alarm and event management– Trending– Scheduling– Remote device and network management

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BACnet Application

• Scope– Scalable from small to large installations– Mainly for large installation– Different buildings using equipments from different

manufactures• Equipments

– HVAC control (Heating, Ventilation and Air-Conditioning, i.e. Climate Control)

– Fire detection and alarm– Lighting control– Security– “Smart” elevators– Utility company interface

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BACnet Protocol

• Set of Hardware + Software of Rules• Apply to

– Electrical Signaling– Addressing– Network Access (Master/Slave, Peer-to-Peer)– Error Checking– Flow Control– Message Sequencing, Segmentation, Check pointing– Presentation Format (Compression, Encryption)– Message Format

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Objects

• Definition – Collection of information related to a particular

function that can be uniquely identified and accessed over a network in a standardized way.

• Objects represent– Physical inputs– Physical outputs– Software processes

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Objects example

• Each object is characterized by a set of “properties” that describe its behavior or govern its operation

Object_Name SPACE TEMP

Object_Type ANALOG INPUT

Present_Value 72.3

Status_Flags Out-of-Service

High_Limit 78.0

Low_Limit 68.0

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Objects Summary

• 23 standard object types– Binary Input/Output/Value– Analog Input/Output/Value– Multi-state Input/Output/Value– Loop– File/Program/– Device…

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BACnet Device

• A collection of objects that represents the functions actually present in a given real device– Device– Loop– Schedule– Group– BI/BO– AI/AO/AV

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Communication

• Client-Server model

• Application Services– Alarm and Event Services– File Access Services– Object Access Services

• Read/Write the properties of an object• Manage objects

– Remote Device Management Services– Virtual Terminal Services

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LAN Options

Network Tech. Introduction Speed

Ethernet 10-100M bps

ARCNET Attached Resource Computer NETwork 2.5 Mbps

LonTalk Part of LonWorks 2.5 Mbps

Master-Slave

/Token-Passing1 Mbps or less

Point-to-Point 115.2 kbps

BACnet/IP • Transporting BACnet messages between IP devices

• A framework embracing other new networking technologies

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Native BACnet

BACnet Workstation

BACnet LAN: Ethernet, ARCNET, LonTalk, MS/TP, LonTalk or BACnet/IP

BACnet Field Panels

Sensors and Actuators

Native BACnet devices provide BACnet communications directly, device to device

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Interconnect Multiple LANs

BACnet Workstation

BACnet LAN: Ethernet

BACnet Field Panels

Sensors andActuators

BACnet LAN: ARCNET


BACnet LAN: MS/PT


Ethernet to ARCNETRouter

Ethernet to MS/PTRouter

BACnet Field Panels

BACnet Field Panels

“Re-package” BACnet messages and re-transmit them unchanged

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Gateways

BACnet Workstation

BACnet LAN: Ethernet, ARCNET, LonTalk, MS/TP, LonTalk

BACnet Field Panels



BACnet to Vendor B Gateway

Non-BACnet Field Panels

Vendor B Proprietary LAN

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Working over IP internet

• IP Message Tunneling– BACnet devices don't know, or need to know,

anything at all about IP

• BACnet/IP– BACnet device is actually a full-fledged IP nod

e, complete with its own IP address and IP protocol stack

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IP Message Tunneling

Annex HRouter

BACnetDevice

BACnetDevice

BACnetDevice

A

Annex HRouter

BACnetDevice

BACnetDevice

BACnetDevice

B

Internet

Net 1

Net 2

1

2

3

4

5

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BACnet/IP

• BACnet + Intrinsic IP– BACnet devices access the IP infrastructure as if it we

re just a different kind of LAN or “virtual data link”– A devices IP address serves the same purpose as a d

evice’s MAC or physical LAN

• BACnet Virtual Link Layer (BVLL)– Deals with specific idiosyncrasies of IP networks, suc

h as broadcast– Encompass virtually any kind of new network technolo

gy or other “micro protocol”• ATM, SONE, ISDN, etc.• Data encryption, data compression• Enhanced security and efficiency measures

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BACnet/IP-Unicast

BBMDBACnetDevice

BACnetDevice

BACnetDevice

BBMDBACnetDevice

BACnetDevice

BACnetDevice

Internet

Net 1

Net 2

BACnet Broadcast Mngt. Device

A

B

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BACnet/IP-Broadcast

BBMDBACnetDevice

BACnetDevice

BACnetDevice

BBMDBACnetDevice

BACnetDevice

BACnetDevice

Internet

Net 1

Net 2


1

2

3

4

A

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BACnet/IP-Foreign Device

BBMDBACnetDevice

BACnetDevice

BACnetDevice

BBMDBACnetDevice

BACnetDevice

BACnetDevice

Internet

Net 1

Net 2


Foreign Devices

Foreign devices can register with certain BBMDs to receive forward broadcast message

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Application Example:

BACnet-Compliant Lighting

• A Lighting Applications Group, Jan. 2001

• Different vendors provides different products– Gateway, Controller, Software

• Example: Synergy Lighting Control System

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Competitor: LonTalk

• Open protocol offered by Echelon– Part of LonWorks

• A LAN specification

• Different control communication

• Different aligned manufactures

• Rapid increase in BACnet installations– a promising indicator of market penetration?

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Summary

• BACnet– BAC Model and Message + Network Layer + LANs– Objects: Representing information– Services: Making requests and interoperating– LANs: Transport system

• Features– No fixed architecture– Object model is easily extended– Doesn’t depend on current technology– Broad participation in its development– Many vendors are committed to it– Global interest

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Supporting Vendor

• Totally nearly 70 by 2/4/06– Controller: BACnet-capa

ble sensors and actuators

– Gateway– Router– Workstation

• Web server

– Tools: Protocol analyzer

Introduction to BACnet Presented by Jianqing Zhang.

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Transcript of Introduction to BACnet Presented by Jianqing Zhang.