Transcript BACnet Basics - KMC Controls - In Touch

BACnet Basics
Ben H. Dorsey III
VP, Marketing & Communications
KMC Controls, Inc.
Preview
BACnet—the standard
BACnet—the community
BACnet—and you
2
Caution
BACnet is BIG
3
Part 1
BACnet—the standard
What is BACnet?
A book
An open standard
A data communications protocol
An acronym: Building Automation and
Control Networks
A means of integrating building systems
A way of life!
5
So . . .
BACnet is a data communications
protocol and an agreed-upon set of
rules for creating interoperable networks
of building systems.
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Encompassing . . .
Building Automation Systems (BAS)
HVAC Central Plant (Chillers, Boilers,
Large Air Handlers)
Lighting
Perimeter and Object Security
Fire and LifeSafety
Elevators
The integration of all of the above.
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Who did it?
A working group (standard project
committee) of the American
Society of Heating, Refrigerating
and Air-Conditioning Engineers
(ASHRAE).
Began work in 1987 under
tremendous opposition (some said
it would NEVER be done).
Published as a standard in 1995.
Supported and maintained by
ASHRAE Standing Standard
Project Committee 135.
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It’s Alive!!!
By design, the standard is under
continual revision.
First published in 1995.
In recent times, most manufacturers’
products have been designed to the
2004 standard.
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Not a Reactive Process
Addenda are issued as the
committee works.
Public review and comments are
mandatory and common.
So, for example, when 2004
was issued, it consisted of 2001
+ previously issued addenda.
(No surprises.)
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What the Standard Defines
In essence, the standard defines the
messages that devices exchange and
how they are delivered.
message
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transport
Further . . .
The rules of the protocol apply to
Electrical signaling
Addressing
Network access (master/slave, peer-to-peer)
Error checking
Flow control
Message sequencing, segmentation,
checkpointing
Presentation format (compression, encryption)
Message format
Source: Mike Newman, BACnet pioneer
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Another Pyramid?
The protocol can be viewed as a matrix of
layers.
BIBBS
Services
Devices
Objects
Properties
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Properties
The nucleus to the
BACnet atom—the
smallest piece of
BACnet information
Properties can be
read and written.
Properties can
provide command
control.
They consist of
names and values.
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BIBBS
Services
Devices
Objects
Properties
Properties
Example: high_limit = 78.0
The standard requires some properties;
other properties are optional; still others
can be proprietary.
Required properties must be
implemented for each object type.
Optional properties do not have to be
implemented, but if they are, they must
conform to the specification.
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Property Identifiers
Property types 0 – 511 are reserved as
standard.
166 of these are currently defined in the
BACnet specification.
Property types above 511 are
proprietary and unique to the vendor.
The Vendor ID property is used to
identify the manufacturer.
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Objects
Objects are the
fundamental building
blocks (atoms) of the
standard.
Objects represent
data that originates in
physical inputs,
physical outputs, or
software processes.
Each BACnet Object
possesses a number
of properties.
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BIBBS
Services
Devices
Objects
Properties
Object Types
The standard specifies 25 types of objects:
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Binary Input
Binary Output
Binary Value
Analog Input
Analog Output
Analog Value
Multi-state
Input
Multi-state
Output
Multi-state
Value
Averaging
PID Loop
Trend Log
Command
Calendar
Schedule
Life Safety
Zone
Life Safety
Point
Notification
Class
Event
Enrollment
Program
File
Group
Device
Pulse
Converter
Accumulator
Objects
Vendors can implement proprietary
object types.
When they do so, they use standard
data types to promote interoperability.
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Object IDs
Numerical identifier that combines
object type and instance number.
Object types 0 – 127 are reserved to
identify standard BACnet objects.
Object types 128 – 1023 are used to
identify proprietary objects.
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Object IDs
BACnet devices will support any mixture
of object types up to a limit of 4,194,303
instances.
Object IDs are typically referred to in
this manner:
Analog Input, 5
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Objects—Summary
Objects standardize the organization of
data to facilitate the exchange of data
between different vendors’ products.
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Devices
There are six device types or
profiles specified by the
standard:
Operator Workstation (B-OWS)
Building Controller (B-BC)
Advanced Application Controller
(B-AAC)
Application Specific Controller
(B-ASC)
Smart Actuator (B-SA)
Smart Sensor (B-SS)
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BIBBS
Services
Devices
Objects
Properties
Services
Think of BACnet
services as the
messages that BACnet
devices send to each
other.
Some services read
and write properties of
one or more objects.
Other services send
notification of alarms or
special events.
Still other services read
and write files.
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BIBBS
Services
Devices
Objects
Properties
Services
BACnet services follow a Client-Server
model.
A BACnet client is a device that requests a
service
A BACnet server is a device that performs
a service
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Categories of Services
Alarm and Event
Routing & event notification
File Access
Accessing & manipulating files contained in devices
Object Access
Read and write properties
Create and delete objects
Manipulate lists of data
Remote Device Management
Remote monitoring and control of devices
Virtual Terminal
Used by a client user to establish a connection to an
application program server in another BACnet device.
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Services—ReadProperty
We wish to read the present value for an analog input called “SPACE_TEMP”
Service= ReadProperty
‘ObjectIdentifier’ = (Analog Input, Instance 5)
‘PropertyIdentifier’ = Present_Value
Operator Workstation
(client)
MS/TP AAC
(server)
Assuming the target machine can locate the object with this ID and the requested properties, the
result would be:
Service= ReadProperty
‘ObjectIdentifier’ = (Analog Input, Instance 5)
‘PropertyIdentifier’ = Present_Value
‘Value’ = 72.3
The result indicates that the present value of “SPACE_TEMP” is 72.3
Source: ANSI/ASHRAE Standard 135-2004, page 494
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BIBBS
BACnet Interoperability
Building Blocks
BIBBS are collections of
services
BIBBS define 5 areas of
interoperability:
Data Sharing
Alarm and Event
Management
Scheduling
Trending
Device and Network
Management
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BIBBS
Services
Devices
Objects
Properties
Data Sharing BIBBS
Description
B-OWS
B-BC
DS-RP-A (read property)
•
•
DS-RP-B
•
•
DS-RPM-A (read property multiple)
•
•
•
DS-RPM-B
B-AAC
B-ASC
B-SA
B-SS
•
•
•
•
•
•
•
DS-RPC-A (read property conditional)
DS-RPC-B
DS-WP-A (write property)
•
DS-WP-B
DS-WPM-A (write property multiple)
DS-WPM-B
•
•
•
•
•
•
DS-COV-A
DS-COV-B
DS-COVP-A
DS-COVP-B
DS-COVU-A (COV, unsolicited)
•
DS-COVU-B
•
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Alarm & Event Management BIBBS
Description
AE-N-A (notification)
BOWS
B-BC
B-AAC
•
•
•
•
•
AE-N-I-B (notification, internal)
AE-N-E-B (notification, external)
AE-ACK-A
•
AE-ACK-B
AE-ASUM-A (summary)
AE-ASUM-B
AE-ESUM-A (enrollment summary)
•
•
AE-ESUM-B
AE-INFO-A
AE-INFO-B
AE-LS-A (life safety)
AE-LS-B
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•
•
•
BASC
B-SA
B-SS
Scheduling & Trending BIBBS
Description
SCHED-A
BOWS
B-BC
B-OWS
B-BC
•
•
T-VMT-E-B
T-ATR-B
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B-SS
•
T-VMT-I-B
T-ATR-A (automated trend retrieval)
B-SA
•
SCHED-E-B (external)
T-VMT-A (viewing & modifying)
BASC
•
SCHED-I-B (internal)
Description
B-AAC
•
•
B-AAC
B-ASC
B-SA
B-SS
Device & Network Management BIBBS
(1 of 2)
Description
BOWS
B-BC
DM-DDB-A (dynamic device binding)
•
•
DM-DDB-B
•
•
DM-DOB-A (dynamic device object)
•
•
DM-DOB-B
•
DM-DCC-A (device communication
control)
•
DM-DCC-B
B-AAC
BASC
•
•
•
•
•
•
•
•
• or
• or
•
•
DM-PT-A (private transfer)
DM-PT-B
DM-TM-A (text message)
DM-TM-B
DM-TS-A (time synchronization)
•
DM-TS-B
DM-UTC-A (UTC time synchronization)
•
DM-UTC-B (UTC time synchronization)
DM-RD-A (reinitialize device)
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•
B-SA
B-SS
Device & Network Management BIBBS
(2 of 2)
Description
BOWS
DM-RD-B
DM-BR-A (backup & restore)
B-BC
B-AAC
•
•
•
•
DM-BR-B
DM-R-A (restart)
DM-R-B
DM-LM-A (list manipulation)
DM-LM-B
DM-OCD-A (object creation & deletion)
DM-OCD-B
DM-VT-A (virtual terminal)
DM-VT-B
NM-CE-A (connection establishment)
NM-CE-B
NM-RC-A (router configuration)
NM-RC-B
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•
•
BASC
B-SA
B-SS
BIBBs Summary Example: B-BC
Data Sharing
Ability to provide the values of any of its BACnet objects
Ability to retrieve the values of BACnet objects from other devices
Ability to allow modification of some or all of its BACnet objects by another device
Ability to modify some BACnet objects in other devices
Alarm & Event Management
Generation of alarm/event notifications and the ability to direct them to recipients
Maintain a list of unacknowledged alarms/events
Notifying other recipients that the acknowledgement has been received
Adjustment of alarm/event parameters
Scheduling
Ability to schedule output actions, both in the local device and in other devices, both binary and
analog, based on date and time
Trending
Collection and delivery of (time, value) pairs
Device & Network Management
Ability to respond to queries about its status
Ability to respond to requests for information about any of its objects
Ability to respond to communication control messages
Ability to synchronize its internal clock upon request
Ability to perform re-initialization upon request
Ability to upload its configuration and allow it to be subsequently restored
Ability to command half-routers to establish and terminate connections
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Transport Options
BACnet IP
BACnet Ethernet (8802-3)
Master Slave/Token Passing (MSTP)
ARCnet
LonTalk
Point-To-Point (PTP)
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Transport Comparison
BACnet IP
Popular, fast. No real
performance difference
between this and 8802-3.
Use BBMD or PAD router to
get across an IP router.
Broadcast issues.
BACnet 8802-3
Popular, fast. No real
performance difference
between this and IP.
Cannot get across IP
routers.
MSTP
Very popular, especially as a
low-level bus technology for
AACs and ASCs. Uses EIA485 signaling over twisted pair
wiring.
Lower performance.
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BACnet Layers vs OSI Layers
Standard OSI Reference Model
Application
BACnet Layers
Presentation
Session
Transport
Network
BACnet Application Layer
Application
BACnet Network Layer
Network
ISO8802-2 (IEE 8802.3)
Type 1
ISO8802-3
(IEE 802.3)
Equivalent OSI Layer
MS/TP
Data Link
PTP
LonTalk
ARCNET
EIA-485
EIA-232
Physical
Data Link
Physical
Source: ANSI/ASHRAE Standard 135-2004, page 9
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Auxiliary Devices
Routers
Useful when networks using different
BACnet transport options need to
exchange data.*
Operator Workstation on
BACnet IP network
Router

BACnet MSTP Controller Network
*This concept is referred to as
“Internetworking.”
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Auxiliary Devices
Gateways
Useful when devices on a BACnet network
must exchange data with devices on a
non-BACnet network.*
Gateway

*This is also
Internetworking.
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BACnet network
Proprietary Network
So, what’s the difference?
A router is really a pass-through device.
It doesn’t change the form or content of
the message but just the packaging—
much like repackaging a standard
USPS letter for sending via Fedex.
A gateway has to translate and is
inherently more complex. It opens the
letter, translates it into a second
language, and puts it back into some
sort of envelope and sends it on.
Source: Mike Newman, BACnet pioneer
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How Does BACnet Work?
•Objects
Application Language
Representing
Information
Making Requests
and Interoperating
•Services
Transport System
•LANs
•Internetworking
Source: David Fisher, PolarSoft
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Typical System View
Operator
Workstation
Management Level
Ethernet or IP LAN
Router
Gateway
Integration Level
MSTP LAN
Proprietary LAN
Field Controller Level
ASCs & AACs
Proprietary Controllers
Application Level
BACnet-enabled Applications & other apps
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Part 2
BACnet—the community
Engineers & Educators
Members of ASHRAE
12 standard regions with 7-16 chapters in each
Beyond America, ASHRAE reaches into Canada
and South America.
Beyond the Americas, ASHRAE reaches into
•
•
•
•
•
•
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Hong Kong
Malaysia
Philippines
Singapore
Taiwan
Thailand
Middle East
India
Africa
Europe
Scandinavia
England
Scotland
Wales
Ireland
SSPC 135
Consists of 7 working groups:
Applications
Lighting Applications
Life Safety & Security
Network Security
Objects & Services
Utility Integration
XML & Web Services
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Manufacturers, Integrators, Owners
BACnet International
Formed in January 2000 to "encourage the
successful use of the data communication
protocol, "BACnet", in building automation
and control systems, through
interoperability and compliance testing,
educational programs, and promotional
activities."
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Corporate BI Members
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Plugfests
Among the many initiatives undertaken by
BACnet International are interoperability
workshops or “plugfests.”
Dozens of member compnaies routinely take
part in these 3-day events for validating
product interoperability.
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Interests Groups
BIGs consist of users, integrators,
manufacturers, contractors, and other
interested parties.
BIG-SU
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BIG-FI
BTL
BACnet Testing Laboratories
Established under direction and
continued supervision of BACnet
International in Feb 2000
“Our goal is to improve
interoperability between BACnet
products through a combination of
BTL lab testing, multi-vendor
interoperability testing, and
adherence to the BTL's device
implementation guidelines.” (Jim
Butler, BTL Manager)
Lists products by issuing mark
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BTL
Has freedom to make requirements
above and beyond the minimum
requirements specified in the standard.
Manufacturers are given pretest
guidelines.
Requires an extended engineering
commitment of manufacturers.
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Part 3
BACnet—and you
BACnet & You
Why go BACnet?
Engineer & owner considerations
Is it really interoperable?
What’s next?
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BACnet Benefits
It is an accepted standard domestically
(ASHRAE/ANSI 135-2004), in Europe
(CEN TC 247), and worldwide (ISO
16484-5).
It was developed specifically for building
systems.
While HVAC is at its roots, the standard
nicely incorporates other integrated
functions.
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BACnet Benefits
It can be implemented on low-cost
networks (dedicated or shared) and is
extremely flexible in LAN types.
BACnet devices are cost-competitive
with long-standing proprietary devices.
The standard specifically provides for
scheduling, trending, and alarming.
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BACnet Benefits
It is easily scalable at all levels for any
size job.
It is completely open and not dependent
on specific hardware.
It provides for automatic device
discovery (saving installation costs).
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BACnet Challenges
It does not specify hardware
configuration. Therefore, configuration
tools (required for initial device setup)
vary by manufacturer.
No standard application types are
defined; therefore, it’s not yet plug-nplay.
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Considerations
Become familiar with PICS
Protocol Implementation Conformance
Statements
Defined format
Specify device type, BIBBS supported,
Object Types supported, and Data Link
layer transport options.
Required for each BACnet device
Available to you
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Considerations
Become familiar with PICS.
Look for “native” BACnet.
Native BACnet typically refers to a device
that inherently represents data in BACnet
format and communicates utilizing BACnet
messaging. Native BACnet devices can be
connected to a BACnet system without
requiring a gateway device or software
driver to translate to and from any
proprietary protocols. (Source: Delta Controls website)
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Considerations
Become familiar with PICS.
Look for “native” BACnet.
Specify BTL listed products.
This is the BACnet community’s seal of
approval.
Note exception for operator workstations
(no testing yet provided).
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Considerations
Become familiar with PICS.
Look for “native” BACnet.
Specify BTL listed products.
Need spec writing assistance?
Do not go to the standard
(at least for this purpose).
Use your manufacturers’ reps.
Try www.ctrlspecbuilder.com.
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Considerations
Become familiar with PICS.
Look for “native” BACnet.
Specify BTL listed products.
Get spec writing assistance if needed.
Use protocol analyzers.
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Considerations
Become familiar with PICS.
Look for “native” BACnet.
Specify BTL listed products.
Get spec writing assistance if needed.
Use protocol analyzers.
Demand training.
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Is it really Interoperable?
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Sample Interoperability
450 Golden Gate, San
Francisco—Phillip Burton
Federal Building
Landmark BACnet installation
using two vendor systems
(Alerton BACtalk and Trane
Tracer Summit) on BACnet
network.
9000 points, over 1000 VAV
terminal units, 8 large AHUs,
13 single-zone AHUs
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Sample Interoperability
Paducah Community College, Kentucky
BACnet installation using two vendor
systems (Alerton and Reliable
Controls) on BACnet network.
6 buildings, 1000 points
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Sample Interoperability
NY Metropolitan Hospital,
Manhattan
BACnet installation using
two vendor systems (Delta
Controls and KMC
Controls) on BACnet
network.
Recent isolation wing
renovation brought KMC
AACs onto the Delta
ORCAview® network.
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Sample Interoperability/Integration
University of Arizona
435 total buildings. BACnet
IP campus WAN
Numerous vendor systems
featuring BMA members
Automated Logic
Corporation and
FieldServer Technologies
ALC’s WebCTRL® manages
the front end. FieldServer
integrates numerous
devices and systems
(including Modbus,
LonWorks, and Simplex)
into the BACnet network.
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Where is BACnet Going?
BACnet support of IP communications
lays the necessary groundwork for
enterprise-wide challenges.
To meet these challenges, however, will
require greater utilization of Internet
protocols developed in the IT realm.
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XML & Web Services
Not really applicable to field-level controllers but highlevel communications.
XML provides for examining high-level data while not
being dependent on the communication protocol of
the BAS, such as BACnet.
So, BACnet manufacturers need to support XML in
the operator workstation, for example.
Further, web services, such as .NET, provide for
greater possibilities in information exchange.
The SSPC 135 XML Working Group is defining how
data can be exchanged consistently between building
automation systems and other enterprise
management systems.
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Further Resources
www.bacnet.org
www.bacnetinternational.org
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So, what are you waiting for?
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