April 2020

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Two Protocols are Better Than NONE

The feedback was important enough that I thought I should publish a revision of the article, sharing what I learned. Thanks to those in the BACnet community and LinkedIn groups who have responded to the original article.
Steve Jones

Steve Jones,
Managing Partner
The S4 Group, Inc

Originally published Feb 2020

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This article was published originally in the February 2020 edition of The Gateway. It did exactly what was intended. It raised awareness of the importance of tagging technology, and it got people discussing how tagging will be delivered. The feedback was important enough that I thought I should publish a revision of the article, sharing what I learned. Thanks to those in the BACnet community and LinkedIn groups who have responded to the original article.

If you are looking for one communications protocol that does everything, for everyone in the BAS industry, all the time, it does not exist!

The front runner is certainly BACnet, as documented by the number of installed systems. The BACnet market share is over 60% globally, and more than 80% North American market share and continues to grow rapidly. BACnet is free to use. The success of BACnet is fueled by the fact that it is an open protocol managed by ASHRAE SSPC 135 (BACnet Committee) and supported by an army of volunteers, BAS companies, and academia. The BACnet committee continues to evolve the standard to meet the ever-changing needs of the industry. The SSPC 135 committee meets quarterly to revise and expand the protocol. BACnet is an ISO standard and is independently testable and certifiable.

BACnet International is an industry association that promotes its use, provides education, testing and certification services. BACnet International oversees the operation of the BACnet Testing Laboratories (BTL) and maintains a global listing of tested products.

Consistent meta-data for sites, devices, and points that convey the function of the objects simply did not exist in the BACnet world. Almost everything in this area was left up to the developer or installer.

Project Haystack evolved as analytics, energy management, and other value-added applications gained momentum in the marketplace. Haystack tagging provides a way of uniquely and consistently identifying objects in a building automation system at all levels of the architecture. The Haystack RESTful protocol was added as a way of extracting tagged data from an automation system for analysis by value-added applications.

With Smart Building, Smart City, and digitalization initiatives gaining momentum, it is hard for the BAS industry to keep up. Cybersecurity is front and center as the most important topic. BACnet SC will address these needs.

Multiple networking transport standards are available to carry the BACnet payload. The BACnet payload is a series of objects, properties, and services that implement the mission of BACnet. The standard does not tell manufacturers how to implement their algorithms or sequences of operation behind the BACnet objects and services. So, it leaves plenty of room for innovation and competition. The BACnet services and transports can evolve independently of each other. So, as stovepiped applications in buildings converge to Smart Buildings and Smart Cities, new objects and services will be added to BACnet.

Similarly, the Haystack community has been very active. The tagging syntax, dictionary, and supporting relationship definitions have evolved as the needs of the value-added applications community have evolved and become more sophisticated. Haystack 4 represents a significant step forward in tagging technology. The most critical open issue in this community is that many value-added applications require a labor intensive and error prone process of manually applying Haystack tags to data before it can be processed.

The latest BACnet standard ANSI/ASHRAE Standard 135-2016 introduced a new optional property to each BACnet object. The TAGS property is an array of tag names and values that describe the characteristics, restrictions, relationships, and semantics of the containing object. BACnet Standard 135-2016 also introduced Annex Y – Abstract Data Model. This Annex defines the methodology for constructing and naming TAGS within BACnet but does not include a tags dictionary. It also provides guidance on how to identify TAGS defined by organizations outside of ASHRAE.

[an error occurred while processing this directive]Since the standard stopped short of providing a tagging dictionary, the adoption level appears to be quite low. However, the functionality is there and should be utilized.In an ideal world there would be one BAS protocol and one tagging dictionary. The BACnet, Haystack, and Brick Schema communities are working together under the auspices of ASHRAE Standard 223P to define a protocol independent TAGGING dictionary. This effort should accelerate the adoption of tagging capabilities into BACnet protocol stacks and client implementations. But this will take time. With most organizations having limited resources, it will probably take longer than anyone would like. However, it is obvious that the commitment to make this happen is there.

Recently, here at S4 we have started looking at BACnet a bit differently than we have in the past. We have been doing it a disservice by treating it only as a communications protocol. It is much more than that. It is an “environment” that enables the implementation of ASHRAE building standards in a way that is Open and Interoperable. BACnet objects and services facilitate local control of building infrastructure for real-time control operations. BACnet transport options provide multiple ways to move the BACnet objects between systems.

We believe that the community does not have to wait for this ultimate solution to evolve. With our release 2.0 we are introducing support for Haystack Tagging and the Haystack RESTful protocol, in addition to support for BACnet. Any integration provided by S4 will automatically include Haystack tagged data. BACnet is available for local control, edge computing, and near real-time algorithms. A periodic maintenance update to our 2.0 product will support the BACnet TAGS property. We realize that only static tags can be assigned by product manufacturers. Additional tags could be assigned because of their relative positions in the networking infrastructure. Still, other tags can only be assigned by the installation engineer, who defines the functionality of the device in the enterprise. Our 2.0 release supports all of these activities.

Two Protocols are better than NONE!


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