Introduction to BACnet

1
Introduction to BACnet

• Presented by Jianqing Zhang

2
Overview

• BACnet Building Automation and Control Networks
• Supported by SPC of ASHRAE since 1987
• Standard Project Committee (SPC) 135P
• American Society of Heating, Refrigerating and
  Air-Conditioning Engineers
• Position
• American national standard
• European pre-standard
• ISO global standard

3
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

4
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

5
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

6
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

7
Objects example

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

8
Objects Summary

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

9
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

10
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

11
LAN Options
12
Native BACnet
Native BACnet devices provide BACnet
communications directly, device to device
13
Interconnect Multiple LANs
Re-package BACnet messages and re-transmit them
unchanged
14
Gateways
15
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 node,
  complete with its own IP address and IP protocol
  stack

16
IP Message Tunneling
A
Annex H Router
BACnet Device
BACnet Device
BACnet Device
1
2
Net 1
3
Internet
4
Net 2
5
Annex H Router
BACnet Device
BACnet Device
BACnet Device
B
17
BACnet/IP

• BACnet Intrinsic IP
• BACnet devices access the IP infrastructure as if
  it were just a different kind of LAN or virtual
  data link
• A devices IP address serves the same purpose as a
  devices MAC or physical LAN
• BACnet Virtual Link Layer (BVLL)
• Deals with specific idiosyncrasies of IP
  networks, such as broadcast
• Encompass virtually any kind of new network
  technology or other micro protocol
• ATM, SONE, ISDN, etc.
• Data encryption, data compression
• Enhanced security and efficiency measures

18
BACnet/IP-Unicast
A
BBMD
BACnet Device
BACnet Device
BACnet Device
Net 1
BACnet Broadcast Mngt. Device
Internet
Net 2
BBMD
BACnet Device
BACnet Device
BACnet Device
B
19
BACnet/IP-Broadcast
A
BBMD
BACnet Device
BACnet Device
BACnet Device
1
Net 1
BACnet Broadcast Mngt. Device
2
Internet
Net 2
3
4
BBMD
BACnet Device
BACnet Device
BACnet Device
20
BACnet/IP-Foreign Device
BBMD
BACnet Device
BACnet Device
BACnet Device
Net 1
BACnet Broadcast Mngt. Device
Internet
Foreign devices can register with certain BBMDs
to receive forward broadcast message
Foreign Devices
Net 2
BBMD
BACnet Device
BACnet Device
BACnet Device
21
Application ExampleBACnet-Compliant Lighting

• A Lighting Applications Group, Jan. 2001
• Different vendors provides different products
• Gateway, Controller, Software
• Example Synergy Lighting Control System

22
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?

23
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
• Doesnt depend on current technology
• Broad participation in its development
• Many vendors are committed to it
• Global interest

24
Supporting Vendor

• Totally nearly 70 by 2/4/06
• Controller BACnet-capable sensors and actuators
• Gateway
• Router
• Workstation
• Web server
• Tools Protocol analyzer