FREE ELECTRONIC LIBRARY - Online materials, documents

Pages:   || 2 | 3 | 4 | 5 |   ...   | 7 |

«Bacnet The Global Standard for Building automation and control Networks BACnet THE GLOBAL STANDARD FOR BUILDING AUTOMATION AND CONTROL NETWORKS H. ...»

-- [ Page 1 ] --

H. MicHael NewMaN


The Global Standard for

Building automation and

control Networks








Writing standards can be frustrating, just as the world was before BACnet! First, there is the

basic problem of trying to reach consensus among the members of a committee, people that may have widely different levels of knowledge, experience, and skill. In the general case, they may also have radically different expectations, goals, and agendas. In spite of this, ways must be found to overcome these differences such that everyone can, at the end of the day, “live with” the result. Hopefully this will ultimately lead to support for the standard against the inevitable slings and arrows that it will face if it is in the least bit controversial, which most standards are, since, by definition, their objective is to limit choice.

Second, the standards writing process can be lengthy. It is much harder than seems. The difficulty is partly because of the technical challenges, which can be formidable. I would say that at least half of the time spent developing BACnet was consumed by having to wrestle with the procedural and bureaucratic challenges presented by the formalities of the standards development process. In the case of BACnet, the standard had to undergo three public reviews, which, in total, generated 741 comments. The response to each comment had to be drafted and thoroughly deliberated within the committee before even being presented to the commenters for their review and, hopefully, approval. All of this was incredibly time consuming, especially when confronted with commenters who were bent on objecting to the standard simply on the grounds that they would have preferred no standard at all.

Third, and most frustrating of all, is that standards writers are not allowed, within the standard itself, to explain why the standard is what it is. Standards are required to be prescriptive:

“this is what you shall do to comply with the standard.” They are to be written in “mandatory xv xvi ·  Preface language.” They are not textbooks or tutorials, and there is certainly no provision for providing any bits of history that might make it clear to someone why a certain requirement is what it is.

Examples, too, are frowned upon although it is possible to include “informative addenda” that contain them.

So one of my main objectives in this book is to explain the BACnet standard, from the point of view of the person who got the ball rolling and kept it rolling from the first committee meeting in the summer of 1987 until the standard was finally published in 1995. I will, of course, get into the bit and bytes of the protocol butwhat I really want to do is give you a seat at the committee table so you can understand why the standard is written as it is. There is a story behind nearly every provision of BACnet, epic struggles in some cases, politics, intrigue, and compromise. If you are not interested in the historical commentary, feel free to skip it. But if you are interested, I hope you will dig in and enjoy it, and, since the story of BACnet is still being written today, you might even consider joining the committee and helping to write some of the next chapters yourself!

KeYWOrDS BACnet, building automation, DDC, data communication protocol, BACS, digital controls, web services, ASHRAE, SSPC 135, ISO 16484-5, ISO 16484-6, ANSI/ASHRAE Standard 135, control networks, BACnet Interest Group, BACnet International CHaPter 1

–  –  –

In this chapter we will begin our BACnet journey together. I will present an overview of the technology and answer some of the most basic questions about the standard and its development, use, testing, supporting organizations, and so on. So let’s go!

1.1 WHat Is BaCnet? a BrIef oVerVIeW There are several answers to this question. First, “BACnet” is an acronym that stands for “Building Automation and Control networking protocol.” A networking or data communication “protocol” is a set of rules that governs how computers exchange information with one another. In BACnet’s case, these rules have been developed by a Standard Project Committee (SPC 135) within the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) starting back in 1987. ASHRAE’s BACnet set of rules has been approved as an American National Standard by the American National Standards Institute (ANSI) and the latest version is formally known as “ANSI/ ASHRAE Standard 135-2012, BACnet—A Data Communication Protocol for Building Automation and Control Networks.” Since the need to continuously enhance and improve the standard was foreseen from the time the very first version of BACnet was published in 1995, ASHRAE formed a “Standing SPC” known as “SSPC 135.” This committee continuously maintains both BACnet and its companion standard, “ANSI/ASHRAE Standard 135.1-2009, Method of Test for Conformance to BACnet.” So BACnet is an acronym, a data communication protocol, a set of rules, and a standard. BACnet-2012 is now a 1039-page document and It is also an ASHRAE publication available in is available directly from the ASHRAE Bookstore.

2 • BaCnet

–  –  –

1.2 tHe BaCnet DeVeLoPMent ProCess Within ASHRAE there are two kinds of standards: those on “periodic maintenance” and those on “continuous maintenance.” The former are subject to reaffirmation, revision, or withdrawal every five years from the time they are first published. The latter, such as BACnet, are continuously maintained. These standards are the responsibility of an SSPC. SSPC 135, or the “BACnet Committee,” currently meets four times a year, at the ASHRAE Winter and Annual Meetings and at two other times, usually hosted by one of the committee member’s companies.

Occasionally, other topics are the subject of a special interim meeting beyond the usual four. In the last few years, for example, there have been several “Alarm Summits” to focus entirely on improving the alarm features of the protocol.


SSPC 135 has three officers, a Chair, Vice-Chair, and Secretary. The members are either voting members or non-voting members. A new and special category of non-voting member is the International Organizational Liaison (IOL). The IOL designation allows the committee to formally recognize the contributions of people representing organizations outside the United States and have their names appear on the official committee roster and in the published standard.

IntroDuCtIon • 3


In order to address specific topics of importance, the SSPC forms “working groups” (WGs) to consider improvements or additions to the standard. These WGs may come and go as issues arise and are addressed. They may also persist indefinitely. The “Objects & Services WG,” for example, is a combination of two of the WGs formed in 1987! Here is a thumbnail description of the WGs currently in place so that you can get an idea of the range of activities being worked on. For updates, visit www.bacnet.org.

AP-WG: Applications

This group is developing applications-oriented “profiles” to represent various building automation devices such as chillers, variable air volume controllers, and variable frequency drives. The group will focus primarily on the user’s perspective while the Objects & Services Working Group will assist by providing the technical details for the final form of the proposals.

DM-WG: Data Modeling

This group was formed in 2012 to take over and expand the work of the XML-WG, which is now defunct. Its task is to develop framework(s) for complex data models both on the wire and in other machine readable formats. It works in cooperation with the other working groups (e.g., AP-WG and SG-WG) to ensure that the framework(s) developed meet the needs of their specific use cases.

EL-WG: Elevator The EL-WG is developing extensions to allow the monitoring of elevator and escalator systems with the BACnet protocol.

IP-WG: Internet Protocol This group has been working on extending BACnet/IP capabilities to deal with developments in the IP world, including Network Address Translation (NAT) firewalls and IPv6.

IT-WG: Information Technology This group is examining the future communication requirements of building automation systems and considering how they might affect BACnet. An important theme for this group is Information Technology-Building Automation System (IT-BAS) convergence.

4 • BaCnet

LA-WG: Lighting Applications

This group is researching, drafting, and proposing additions to the BACnet standard to support the requirements of lighting control applications. The group is working in cooperation with the National Electrical Manufacturers Association (NEMA) Lighting Control Council and the Illumination Engineering Society Controls Committee.

LSS-WG: Life Safety and Security

This group will research, draft, and propose additions to the BACnet standard to support the requirements of life safety and security applications. The first systems to be tackled were fire alarm and control systems. The group has developed several new objects and services to this end.

MS/TP-WG: Master-Slave/Token-Passing This group works on enhancements and issues relating to BACnet MS/TP LANs and PTP communications.

NS-WG: Network Security This group was formed in response to public review comments about managing the primary workstation in life safety emergencies. Their task is to develop a general, network visible mechanism for authorizing and transferring control authority and also to develop auditing mechanisms.

OS-WG: Objects and Services This group concentrates on “infrastructure” modifications needed to support new objects, new services, or refinements to existing objects and services.

SG-WG: Smart Grid This group is a continuation of the previous Utility Integration Working Group with a new name.

Smart Grid is all about integrating the consumer as an active participant in the operation of the electric grid. This includes integration of facility load as a resource (demand response), customer owned generation (distributed generation), and customer owned storage (electrical, thermal, pumped water, etc.). The SG-WG is focused on enabling the building to act as a full participant in the grid—receiving price and event signals from grid operations as well as requests for resource status—and responding to grid signals with control actions to appropriately manage energy. In addition, this group is working to ensure that BACnet will be able to support the data structures being developed by ASHRAE SPC 201P, the Facility Smart Grid Information Model (FSGIM). The model includes definition of loads, meters, generators, and energy managers

IntroDuCtIon • 5

that will facilitate developing the ability for BACS to respond to demand response events in an automatic manner, such as altering setpoints, rescheduling equipment operation, etc., in order to lower demand.

TI-WG: Testing and Interoperability This group’s mandate is to extend and maintain Standard 135.1—the BACnet testing standard, to extend and maintain the BACnet Interoperability Building Block definitions and Device Profiles, and to identify and resolve existing interoperability issues in the BACnet standard itself.

WN-WG: Wireless Networking (inactive) This group investigated the use of BACnet with wireless communication technologies such as ZigBee, the 802 series of wireless Ethernet, and others. It produced Annex O—BACnet over ZigBee as a Data Link Layer.

XML-WG: XML Applications (work transferred to the new DM-WG) This group investigated applications of the “eXtensible Markup Language” (XML) technology in relation to BACnet systems.

As you can see, there are enough topics to keep everyone busy for a long time.

1.2.3 CONTINUOUS MAINTENANCE So, how are changes to the standard actually made? Since BACnet is under continuous maintenance (CM), anyone, anywhere, can submit a suggestion for a change at any time. In practice, most change proposals have come from committee members or their colleagues. The proposer writes up his/her proposal with some background information so the committee can understand why the proposal is being made along with recommendations for specific changes. It is then usually doled out to one of the WGs for detailed review. To keep track of the hundreds of proposals that have been made over the years, the SSPC has adopted some proposal naming conventions. Each proposal name starts with the initials of the proposer, a sequence number, and a revision number. The first draft of my third proposal would be of the form “HMN-003-1.” If, after reviewing my proposal, the WG directs me to make some changes, I would submit “HMN-003-2.” Eventually, with any luck, the WG would see the wisdom of adopting my proposal and would pass it on to the full SSPC for a final vote. The next step is to invite the “public” to review it.

Another aspect of the CM process is to issue “interpretations” of the standard. Like change proposals, interpretation requests can be submitted to the SSPC at any time and are in the form of statements about specific wording in the standard followed by the question “Is this interpretation correct?” The SSPC must then rule “Yes” or “No.” Often such requests arise from perceived ambiguities in the standard’s language and lead to clarifications of the standard’s intent.

6 • BaCnet A final activity is to collect together, from time to time, any errors that have been noticed in the standard and that can be considered typographical or non-substantive, i.e., correcting them has no affect on compliance with the standard. This would include things like misnumbered clause references, misspellings, missing details in a revision history, incorrect indentation levels in a table, etc. These errors are then collected together and published as “errata” every year or so.

Pages:   || 2 | 3 | 4 | 5 |   ...   | 7 |

Similar works:

«The current issue and full text archive of this journal is available at http://www.business.brookes.ac.uk/research/areas/coachingandmentoring/ International Journal of Evidence Based Coaching and Mentoring Vol. 10, No. 1, February 2012 Page 33 Coaching as dialogue: Creating spaces for (mis)understandings Hilary Armstrong, Institute of Executive Coaching, Sydney, NSW, Australia Contact Email: hilarya@iecoaching.com Abstract This paper considers dialogue as the central motif of coaching. Taking a...»

«Lolita 2.0. Nymphets on the silver screen. Anna Pilińska Abstract In 1955, the reading audience meets Dolores Haze – a character whose Nabokovian beginnings can be traced back to “The Enchanter” (1939) or even to one of the author’s Russian short stories, “A Nursery Tale” (1926). Filtered through the unreliable narration spun by Humbert Humbert, Lolita somehow loses her status of a victim and eventually becomes synonymous with a precocious, perversely seductive young girl. The...»

«UNREPORTED IN THE COURT OF SPECIAL APPEALS OF MARYLAND No. 1088 September Term, 2013 TASHA STEWART A/K/A TASHA KILAN BENJAMIN v. AYINDE STEWART Zarnoch, Wright, Raker, Irma S. (Retired, Specially Assigned), JJ. Opinion by Wright, J. Filed: July 30, 2014 On August 4, 2011, appellant, Tasha Stewart (“Wife”), filed a complaint for an absolute divorce against appellee, Ayinde Stewart (“Husband”), in the Circuit Court for Anne Arundel County. On September 16, 2011, Husband filed a...»

«^ Z, ^ z Z  KE ^Z, /^^E ' z  W  Izdaje i tiska Državni zavod za statistiku Republike Hrvatske, Lektorica za hrvatski jezik/ Croatian Language Editor: Zagreb, Ilica 3, p. p. 80 Anđa Matić Published and printed by the Croatian Bureau of Statistics, Korektorica za hrvatski jezik Zagreb, Ilica 3, P.O.B. 80 Croatian Language Proofreader: Anđa Matić Odgovara ravnatelj dr. sc. Ivan Kovač. Prevoditeljica i lektorica za engleski jezik Person responsible: Dr. Ivan Kovač, Ph.D., Director...»

«      Impressoras Argox Manual de Programação Linguagem PPLA Revisão 1.1 Julho 2002 Torres Indústria e Comércio de Etiquetas e Adesivos Ltda. Rua Odorico Mendes, 325 – Bairro Moóca – São Paulo – SP Web site: www.torres.ind.br e-mail: torres@torres.ind.br Telefone: (11) 3346-6900 Fax: (11) 3209-8972       Índice Leia esta página antes de iniciar Programando através do MS-DOS Comandos de controle...»

«Office of the Inspector General U.S. Department of Justice Audit of the Office of Justice Programs Victims of Crime Act Grant Sub-Awarded by the California Governor’s Office of Emergency Services To Two Feathers Native American Family Services McKinleyville, California Audit Division GR-90-16-004 March 2016 AUDIT OF THE OFFICE OF JUSTICE PROGRAMS VICTIMS OF CRIME ACT GRANT SUB-AWARDED BY THE CALIFORNIA GOVERNOR’S OFFICE OF EMERGENCY SERVICES TO TWO FEATHERS NATIVE AMERICAN FAMILY SERVICES...»

«Love and Death in Early Modern Marriage: The Winter’s Tale and Monumental Sculpture 1 Catherine Belsey This article attributes early modern emotional relationships between parents and children, as well as between marital partners, to the emergence in the period of family values. While the stability of the ideal family is defined in tomb sculpture, one of the period’s most widespread art forms, plays tell a story and therefore depend on impediments to stability. These are dramatised in the...»

«MEGASHIFT or MEGAHYPE ? By Shaun Kearney GOD MOVED MAN MOVED IN GOD QUIT HAS THERE EVER BEEN A VISITATION YET THAT MEN HAVEN’T HIGHJACKED? Much “ado” about nothing? A move away from big gatherings in church buildings to homes has been experiencing exponential growth worldwide. A lot of discussion is going on presently over the airwaves about a “Megashift” that’s taking place in Christianity. Great store is being placed on relocating to homes. If we are to accept the reports coming...»

«Progress Report of the Department of Accounting for the 2016 1. Produce High Quality Human Resources (Teaching and Learning) Inauguration ceremony of the Diploma in Computer Based Accounting 8th Intake was • held on Sunday 10th January 2016. This time department selected 87 students for the course. A 4-day skill development training workshop for enhancing auditing skills titled • ‘Improving Audit Skills – Training Program’ was organized by the Department of Accounting and was...»

«Soldiers of Odin USA The Extreme European Anti-Refugee Group Comes to America Only months after its formation in Finland, a controversial anti-refugee vigilante group known as the Soldiers of Odin has already found a welcome home in the United States. Its new American chapter, known as Soldiers of Odin USA, has—just since February—already amassed thousands of American members and cheerleaders ready and eager to support the group’s chapters in Finland and other countries— and to bring...»

«ANNEX 1 Analysis of scientific literature Ref. Authors Title Source [McE98] R.P McEnaney, Experimental comparison of mobile A/C 1998 International D.E Boewe, systems when operated with transcritical Refrigeration Conference J.M Yin, Y.C Park, CO2 versus conventional R-134a at Purdue C.W Bullard, P.S Hrnjak [ACR02] ACRC SAE alternate refrigerant Cooperative SAE cooperative Research Project research program. November 2002 [BRO02] Brown J.S., YanaComparative analysis of an automotive air...»

«LV EIROPAS SAVIENĪBAS PADOME C/04/172 Luksemburgā, 2004. gada 2. jūnijā 9779/04 (Presse 172) PRESES RELĪZE 2587. Padomes sanāksme Ekonomikas un finanšu jautājumi Luksemburgā, 2004. gada 2. jūnijā Priekšsēdētājs Charlie McCreevy, TD Īrijas Finanšu ministrs PRESE Rue de la Loi 175 B – 1048 BRUSSELS Tel.: +32 (0)2 285 60 83 / 6319 Fakss: +32 (0)2 285 8026 press.office@consilium.eu.int http://ue.eu.int/Newsroom 9779/04 (Presse 172) LV Galvenie Padomes darba rezultāti Padome...»

<<  HOME   |    CONTACTS
2017 www.thesis.dislib.info - Online materials, documents

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.