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The BACnet Protocol and InduSoft Web Studio

Written by Paulo Balbino, developer at InduSoft

What is BACnet?

BACnet is a communication protocol  for building automation and control networks. BACnet is ASHRAE, ANSI and ISO standardized. Developed under the auspices of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), BACnet is an American national standard, a European standard, a national standard in more than 30 countries, and an ISO global standard. The protocol is supported and maintained by ASHRAE Standing Standard.

Created in June of 1987, after about eight years of development, the BACnet protocol is now present in many vendors’ devices internationally, and is used in many industrial and corporate buildings and airports.

Why to use BACnet?

The interconnection between many different devices that use different protocols is possible, but is often associated with a heavy cost, and almost always uses gateways and converters. If only one protocol is used, the management and control is much more straightforward.

Benefits of a Standard Protocol (BACnet)

  • Single Operator Workstation
  • Competitive system expansion
  • Possibility of integrating all BAC functions
  • Interoperability

Where it is used?

The protocol is designed to be applicable to all building automation needs; to accomplish this, the BACnet protocol specifies all the common desired functions for building automation.  These include: analog input, output and values, control loops,  and schedules. Due to its great specification, the protocol can be used in all building automation applications like  HVAC control, alarms, heating, ventilating, air-conditioning control, lighting control, access control, smart elevators, utility company interfaces and fire detection systems and their associated equipment.

BACnet in the world

The BACnet protocol has become important globally. It was translated into several different languages ​​like Chinese ,Japanese and Korean, and interest groups were formed in North America, Europe Australia and over the Pacific area. In the future, it’s expected that BACnet will expand in importance to China.

Protocol Rules

BACnet is special among protocols because its message format was specifically designed to facilitate communication about information related to building automation and control. The protocol has the following rules:

  • Eletrical Signaling
  • Addressing
  • Network Access (Master/Slave, Peer-to-Peer)
  • Error Checking
  • Flow Control
  • Message Sequencing, Segmentation, Checkpointing
  • Presentation Format (Compression, Encryption)
  • Message Format

Objects

The BACnet object is simply a collection of information related to a particular function that can be uniquely identified and accessed over a network in a standardized way. All information in a BACnet system is represented by such data structures. The object concept allows us to talk about and organize information relating to physical input and output, as well as non-physical concepts like software or calculations. BACnet defines 23 objects:

BACnet objects in InduSoft SCADA software

BACnet objects

InduSoft and BACnet

InduSoft has supported BACnet since 2005, and is improving the driver, adding some features like a Scheduler, and supporting and releasing it for  Win CE and XP.

InduSoft reformulated and extended the BACNE driver, dividing it into two drivers. One of them is BACNE,  which has the function of a Workstation acting as a Master, and supports the following interfaces:  MS / TP and BACnet / IP.  The other driver BACSL, which is a slave and can serve as a gateway interfacing other protocols through its wide range of supported drivers.

BACnet objects in InduSoft SCADA software

Diagram: LOW END BLIND DEVICE WORKING AS A GATEWAY RUNNING WITH CE VIEW

InduSoft can provide data from the BACnet driver via the Web, and then the user can control and monitor data remotely using remote devices like PDAs and cell phones like the iPhone by using the SMA Technology.

Usability

The advantages offered by the BACSL and BACNE drivers are not limited to interfaces, but also includes the broad support to the most important objects and properties, which offers strong usability in terms of configuration and use of the driver. The interface information can be changed graphically in engineering mode, providing the user the possibility to choose between the (MS / TP and BACnet / IP). As for the connection information, for example, to choose the destination device the user only needs to add in the station field, and the number of the Network and Device ID separated by a semicolon. The user does not need worry about the IP of the device with these two pieces of information. Services such as Who-IS can ensure that the message is delivered to the correct recipient.

InduSoft completes the objects and properties that are typed in the address field, facilitating the user’s work and increasing their productivity and agility in making applications.

The interfaces supported by the  BACnet drivers and InduSoft cover the most important interfaces and interconnections used in terms of building and HVAC (MS / TP and BACnet / IP). However, we are open to new requirements (challenges), and InduSoft supports interfaces, objects and services. If you wish InduSoft to support a new requirement, object, property, service or interface, please contact us.

A Beta version of the BACSL is already available. To test this driver, simply contact us at info@indusoft.com and request it.

Visit us on:  www.InduSoft.com.br

References

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