A brief presentation of BACnet standard followed by how it has been updated to be used in IT environments in the form of BACnet-IT.

1. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering© 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Distributed Embedded Systems
BACnet/IT
Preetham Rengarajan Kannan (217205505)
Pradeep Siddagangaiah (217205702)
04.06.2018 1

2. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
BACnet
04.06.2018 © 2018 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 2
• Building automation communication Protocol for Building Automation and Control
Networks.
• It is intended to provide interoperability between different vendors equipment.
BACnet
Source: Slide 2 and 5 in [1]

3. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Overview of a BACnet System
12.10.2015 © 2018 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 3
• Routers
• Gateways
• Different communication networks
• Object oriented Information Handling
Device
Services
PROPERTY
PROPERTY
Object 1 Object 1
PROPERTY
PROPERTY
Source: [5]

4. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
BACnet/IT
04.06.2018 © 2018 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 4
• BACnet provides some limitations in an IT environment:
 Fixed IP addresses
 Broadcasts that may propogate through the entire network
 Excessive use of IT administered IP addresses
• BACnet/IT overcomes them by having several features intended for an IT environment
BACnet/IP Stack BACnet/IT Stack
BACnet Application Layer
BAC net Network Layer
Ethernet
BZLL
BVLL
v6
BVLL
LONTalk
PTP
MS/TP
ARCNET
BACnet Application Layer
BACnet/IT Layer
WebSocket DNS-SD …
TCP-UDP-TLS-DTLS
IPv4-IPv6
IP Capable Datalinks & Physical Layers
UDP
IPv4
UDP
IPv6
UDP
IPv4

5. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Communication in BACnet/IT
04.06.2018 © 2018 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 5
• Communication using a numerical Device ID
• BACnet broadcast using a Device Group ID.
• For flexiblity and scalablity, the logical identifies of Devices and Device groups are
considered to BACnet EID (Entity Ids)
• For communication to take place a EID is resolved to a URL. An example URL for the
Websocket port is given below
Scheme Authority Path
wss://thecontroller.com/site/bacnet/devices

6. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Transport and Directory Port
12.10.2018 © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 6
T-SAP D-SAP
BACnet/IT Layer
• Transport Port implements an
application of application layer
using service primitives
• A set of service primitives makes
up Transport access point (T-
SAP)
• Directory port implements the
directory functionality
• D-SAP interface peforms the
functionolity of resolution of EID
to URL and discovery of devices
BACnet Application Layer
WebSocket
Transport Port
WebSocket DNS-SD …
DNS-SD
Directory Port
Future Ports

7. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Transport and Directory Port
04.06.2018 © 2018 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 7
WebSocket Transport Port
• It is web technology for providing communication channel over a
TCP or TLS connection
• Security can be provided to the data transmitted through encryption
and authentication
DNS-SD Directory Port
• The DNS Service Discovery API helps you to perform three main
tasks:
• Registering a service
• Browsing for services
• Resolving service names to host names
• Each BACnet service is identified by the protocol used. There is
differentiation of devices and devices groups.
• Example: dev._sub._bacnet._tcp
Websocket
envelope
TCP/IP
envelope
Send Receive
Data

8. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Interconnect BACnet in a BA Network
12.10.2015 © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 8
BACnet/IT devices in a BACnet System Source: Figure 2 of [3]

9. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Mini Project Topic
04.06.2018 © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 9
• A client server communication using Bacnet/IT – Simulate a read property
message.

10. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
References
04.04.2018 © 2018 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 10
[1] http://www.bacnet.org/Tutorial/HMN-Overview/sld002.htm
[2] http://www.bacnet.org/Bibliography/EC-9-97/EC-9-97.html
[3] http://www.bacnet.org/Bibliography/BACnet_IT_WhitePaper_2016121.pdf
[4] http://www.bacnet.org/Bibliography/EC-9-97/EC-9-97.html
[5] http://www.bacnet.org/Bibliography/EC-9-97/EC-9-97.html

11. © 2015 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and Computer Engineering
Transport Port
04.06.2018 © 2018 UNIVERSITY OF ROSTOCK - Department of CS and EE - Institute of Applied Microelectronics and CE 11
• A transport port implements a defined application of an IP applicaion protocol for
BACnet/IT
• The interface of transport port is made up of Service Premitives. The following set of
service primitives makes up the transport service access point (T-SAP)
• Any BACnet message sent through a transport port is formatted as BACnet Transport
Protocol Data Units (TPDU) and are binary encoded. The below figure represents the
body of TPDU header. In this header, R represents required paraments and O represents
optional parameter
Primitive Purpose
T-CONNECT/DISCONNECT.request Request the establishment/disconnection of an outbound connection
T-CONNECT/DISCONNECT.confirm Indicate the establishment/disconnection of an outbound connection
T-CONNECT/DISCONNECT.indication Indicate the establishment/disconnection of an inbound connection
Version-R Priority - O Destination
EID- R
Orginal
Desitnation
EID - O
Source
EID - R
Invoke ID -
R
Sequence
Number –
O
Forwards –
O
Security
- O