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2 min read

What is BACnet Part 1

By Phil Zito on May 6, 2013 12:11:26 PM

What is BACnet

This article is part of a four-part series on BACnet; you can access the other parts below:

BACnet Part 2: Communication 101
BACnet Part 3: BACnet/IP
BACnet Part 4: BACnet/MSTP

BACnet is the most prevalent protocol in the building automation space, but to many, it is a six letter word that screams confusion! In this series we will dig deep into what BACnet really is and what it isn't. By the end of the series, you will be able to confidently communicate:

  • What BACnet is
  • Why It is used
  • How it applies to you

Part 1 What is BACnet?

BACnet Stands for Building Automation and Control Networks. BACnet was formed by ASHRAE in 1995 as Standard 135.

The current Addenda of BACnet is Addendum 135-2010aa links to all of the BACnet addendums can be accessed Here.

BACNet is a communication protocol this is not to be confused with Niagara which is a framework.

A Protocol is a set of rules that applies to the following:

• Signaling
• OSI layers- MAC/Physical
• Error Checking
• Flow Control
• Messaging (to include sequencing and message format)
• Presentation

BACnet in its truest form was developed to provide a standardized approach to networks, messages, and data links. BACNet achieves this standardized approach by utilizing "objects".

BACNet Objects

Objects are according to the BACnet standard " a collection of information related to a particular function that can be uniquely identified and accessed over a network in a standardized way"

• An object will provide a set of properties that contain data related to that object.
• BACnet has a set of 23 standard objects.

A deeper dive into objects, properties, and services can be accessed Here.



A simple definition of a BACnet device is a collection of objects that represent the functions present in a real device. This is why virtual devices can be considered a BACnet device as well as physical controllers. The device is defined by the objects inside not its physical architecture.

BACnet LAN Types

BACnet currently supports five LAN types for communications

• BACnet over IP (Annex J)
• BACnet over Ethernet
• BACnet over Master Slave/Token Passing MS/TP
• BACnet over Point-to-Point (PTP)
• BACnet over ARCNET


So there you have it, in 350 words you learned a slew of information around BACnet. Throughout this series, you will learn about how BACnet communicates both across IP and MS/TP.

P.S. Want a deeper dive into BACnet? This article includes a small portion of what we cover in SBA's Definitive Guide to BACnet, check it out.

Have other questions? Let me know in the comments below!


Phil Zito

Written by Phil Zito

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