New developments in the field of BACnet protocol integration.
Work on the implementation of the BACnet protocol covers all areas of building and structure construction.
When the BACnet protocol development committee (an abbreviation for Building Automation Control Network – a communication protocol for building automation) was formed in 1987, its members had a clear idea of the task: to unite all elements of building automation with a single network protocol.
The process was slow and arduous, but significant progress was made in this direction — several possible extensions of the BACnet standard were proposed as an attempt to integrate uncovered areas of building automation.
The committee developing the protocol included mainly representatives from manufacturers of air conditioning, ventilation and heating (HVAC) systems.
When the BACnet protocol was being approved (see ANSI/ASHRAE/IESNA standard 135, BACnet – A Data Communication Protocol for Building Automation and Control Networks), it was well suited to the needs of HVAC system manufacturers.
Later, representatives of fire and security system manufacturers joined the committee and their requirements were also added to the text of the standard (2001 edition).
Around that time, the tasks of the committee working groups already included the integration of power supply systems, lighting control, physical access to premises, and the refinement of BACnet communication security tools.
A couple of working groups have developed additions that have been approved as annexes to the standard, and others are also close to fulfilling their intended purpose.
Access Control
In 2006, the Life-Safety and Security Working Group (LSS-WG) released its first draft of the Access Door standard, which provided specifications for a BACnet door control system.
The Access Door problem statement was approved in Appendix F of Standard 135-2004, but it represents only a small portion of the work being done by the groups.
In March 2007, the LSS-WG submitted seven more drafts for public review and comment.
This is part of a well-established process that all new drafts submitted for approval go through.
The essence of these projects is to introduce an Access Point, Access Zone, User Access, Access Credential, Access Rights and Login Identification.
It is also proposed to develop an access algorithm.
A complete set of extensions is necessary for full support of the operation of physical access control systems using the BACnet protocol.
These proposals were developed in collaboration with industry representatives working in the areas of access control and building automation.
The participation of access control experts ensured that the standard would incorporate the latest technology from the industry.
By creating access control software applications within the BACnet protocol, the LSS-WG was able to take advantage of existing work by the BACnet committee as well as work in progress by other working groups.
This allowed the LSS-WG to focus entirely on the physical access control elements.
The rapid completion of this working group's project will also be facilitated by both a clear definition of the entire network structure and a description of the systems as a whole.
The members of the LSS-WG working group point out another advantage of implementing a physical access control system based on the BACnet standard: when developing and deploying such a system, its elements can be integrated directly into the equipment of existing (and there are many of them installed) automation systems within the BACnet standard around the world.
Securing network communication
Another additional protocol extension, without which physical security control is impossible, is being developed by the NS-WG working group, which deals with network security issues (an abbreviation for Network Security Working Group).
This working group is developing alternative mechanisms for implementing cryptographic protection and authentication within the network communications framework of the BACnet Standard 135-2004.
In March 2007, the NS-WG submitted its proposals for public review and public comment in the form of a document, BACnet Network Security.
When the foundations of BACnet security were being developed, the work was carried out on the basis of the previous cryptographic standard, DES (Data Encryption Standard).
However, the improvement of computer technologies has led to the fact that previous security standards no longer provide the necessary level of security.
The NS-WG is developing an alternative security implementation mechanism based on the newer AES (Advanced Encryption Standard) standard, approved for use by the US Government.
The advantage of the AES standard is higher performance on the same software and hardware.
It can easily be implemented on relatively low-power BACnet controllers, which is practically impossible in the case of the DES standard.
The use of AES allows for secure communications within the BACnet network, at all levels down to relatively inexpensive controllers on the MS/TP (masterslave/token-passing) bus with an RS485 interface.
In fact, the development of the BACnet Network Security system began even before the physical access control system project appeared.
You can imagine the complexity of developing a network security system from the fact that the description of information security and authentication methods in the BACnet protocol alone takes up more than 50 pages, while all seven other extensions devoted to access control take up 64 pages.
Integration of Utility Supplies The UI-WG (abbreviation for Utility Integration Working Group) deals with issues of integrating utility supplies into building automation systems.
In 2006, the UI-WG released its first proposals for an extension to the BACnet protocol (the Load Control task), which was included as an appendix in the 135 standard.
Previously, some manufacturers had been developing their own means of providing control over the energy supply of buildings, but only Load Control provided a standardization of such control means, allowing them to interact with energy supply organizations.
The UI-WG continues to develop a detailed protocol for exchanging information in the power supply network to implement real-time energy consumption metering within building management systems.
Since this is part of the scope of tasks of power supply systems, the need for the UI-WG arose.
Some interesting forms of cooperation between the UI-WG and other working groups show the value of joint efforts to integrate all building automation systems based on a single protocol.
Thus, one of the proposals of the UI-WG group is about using BACnet Web Services and BACnet Network Security to organize information exchange within the building.
Last year, in response to a request for specific energy capabilities, the text of the Structured View task was published.
The solution to this problem will help the Applications Profile Working Group develop standard BACnet requirement profiles for items such as motor frequency converters or VAV (variable air volume) controllers.
Lighting Systems Integration The LA-WG (short for Lighting Applications Working Group) is working on the integration of lighting control systems using the BACnet protocol. In March 2007, the group released details of its project for public comment.
The developments of this group are directly related to the creation of lighting controllers from the simplest, such as analog switches, to much more advanced ones, allowing continuous regulation of illumination, increasing illumination at a certain rate, setting a fixed period of lamp fading, stepwise increasing or decreasing illumination.
The project of this group, presented for public discussion, includes a description of a class of lighting devices that meets the requirements of direct switching and dimming.
The working group proposed a solution in the form of a network layout that runs from the gateway to the actual lighting network, equipped with a system based on the interface with digital control of light sources (Digital Addressable Lighting Interface).
The LA-WG is also preparing other projects for public discussion.
These include such an extension of the BACnet standard as a scheduler tied to events (an example could be the onset of dusk or dawn).
It also provides for the transmission of commands for lighting control via a radio channel.
This is possible even in slow BACnet networks, such as those based on the MS/TP bus.
Conclusion
Although the BACnet protocol was initially developed primarily by manufacturers of equipment for the automation of air conditioning systems (HVAC), according to the BACnet committee, there is a pressing need to set the task of integrating such systems together, namely: fire protection and security systems, physical access control systems, lighting and energy consumption.
Work is also underway in other areas, such as: developing user profiles, using the wide capabilities of the Internet, including wireless solutions.
The implementation of current plans for the integration of the BACnet protocol will undoubtedly be further developed in all areas of building automation.
About the author: Bill Swan, Chairman of the BACnet Committee of SSPC 135 ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), Service Engineer (Alerton/Honeywell International)