SIST EN ISO 16484-5:2026
(Main)Building automation and control systems (BACS) - Part 5: Data communication protocol (ISO 16484-5:2026)
General Information
- Abstract
The purpose of this document is to define data communication services and protocols for computer equipment used for monitoring and control of HVAC&R and other building systems and to define, in addition, an abstract, object-oriented representation of information communicated between such equipment, thereby facilitating the application and use of digital control technology in buildings.
- Status
- Published
- Public Enquiry End Date
- 24-Jun-2026
- Publication Date
- 07-Sep-2026
- Technical Committee
- OGS - Heating for buildings
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 02-Sep-2026
- Due Date
- 07-Nov-2026
- Completion Date
- 08-Sep-2026
Overview
SIST EN ISO 16484-5:2026 defines the data communication protocol for Building Automation and Control Systems (BACS). Developed by the Slovenian Institute for Standardization (SIST) and aligned with international standard ISO 16484-5:2026, this standard sets the requirements for data communication services and protocols used to monitor and control building systems such as HVAC&R (Heating, Ventilation, Air Conditioning, and Refrigeration) and related subsystems. It also introduces an abstract, object-oriented approach for information exchange, enabling more efficient digital control across various building technologies.
This standard is essential for equipment manufacturers, system integrators, designers, and facility managers who need to ensure seamless interoperability and integration between different brands and types of building automation equipment.
Key Topics
- BACnet Protocol Architecture: Outlines the open communication framework for BACS, detailing the various network topologies, collapsed architecture, and built-in security provisions.
- Layered Communication Model: Defines application, network, data link, and physical layers supporting multiple technologies including Ethernet, ARCNET, MS/TP, Point-to-Point, and LonTalk networks.
- Object-Oriented Data Representation: Provides a model for representing devices and their data as well-defined objects, such as analog and binary inputs/outputs, schedules, trend logs, alarms, and access control points.
- Alarm, Event, and Audit Services: Specifies services for monitoring, event notifications, audit trails, and handling of alarms within building systems.
- Access and File Services: Details how systems can securely retrieve, update, and manage files and objects, supporting holistic device management and data integrity.
- Authentication and Authorization: Addresses mechanisms for verifying user and device identities and managing access rights to secure critical building operations.
- Error Handling and Logging: Standardizes error, reject, and abort codes to ensure systems handle exceptions consistently and effectively.
Applications
Implementing SIST EN ISO 16484-5:2026 delivers significant benefits for various sectors within the building and construction industry:
- Seamless System Integration: Enables diverse devices from multiple vendors to coexist and operate as a unified system-important in smart buildings and complex facilities.
- Future-Proof Building Infrastructure: The abstract, object-oriented model makes it easier to adapt systems to evolving technologies and industry requirements.
- Enhanced Building Performance: Reliable and standardized data communication helps optimize HVAC&R performance, energy management, lighting, security, and access controls, improving comfort and efficiency.
- Simplified Maintenance and Upgrades: Standardized protocols and object models reduce downtime and compatibility issues during system upgrades or expansions.
- Regulatory Compliance: As the standard may be referenced in national and international regulations, early adoption helps meet compliance and market requirements.
Related Standards
Professionals working with SIST EN ISO 16484-5:2026 may also benefit from familiarity with the following standards:
- ISO 16484 Series: Covering holistic BACS design, installation, and commissioning processes.
- ISO 8802-3 (Ethernet): Referenced within BACnet for physical and data link layer compatibility.
- ISO/IEC 14908-1 (LonTalk): Used for certain network types within building automation.
- IEC 61131: Relevant for programmable controllers commonly used in automation systems.
- EN 15232: Focuses on the energy performance of buildings through automation and control systems.
For industry professionals seeking to design, implement, or manage advanced building automation, adopting SIST EN ISO 16484-5:2026 ensures a scalable, interoperable, and secure foundation for intelligent facility management.
Relations
- Effective Date
- 01-Oct-2026
- Effective Date
- 02-Sep-2026
- Effective Date
- 02-Sep-2026
- Effective Date
- 02-Sep-2026
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Frequently Asked Questions
SIST EN ISO 16484-5:2026 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Building automation and control systems (BACS) - Part 5: Data communication protocol (ISO 16484-5:2026)". This standard covers: The purpose of this document is to define data communication services and protocols for computer equipment used for monitoring and control of HVAC&R and other building systems and to define, in addition, an abstract, object-oriented representation of information communicated between such equipment, thereby facilitating the application and use of digital control technology in buildings.
The purpose of this document is to define data communication services and protocols for computer equipment used for monitoring and control of HVAC&R and other building systems and to define, in addition, an abstract, object-oriented representation of information communicated between such equipment, thereby facilitating the application and use of digital control technology in buildings.
SIST EN ISO 16484-5:2026 is classified under the following ICS (International Classification for Standards) categories: 35.240.67 - IT applications in building and construction industry; 97.120 - Automatic controls for household use. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN ISO 16484-5:2026 has the following relationships with other standards: It is inter standard links to SIST EN ISO 16484-5:2022, SIST EN ISO 16484-3:2005, SIST-TP CEN/TR 18081:2024, SIST EN IEC 60730-1:2025. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
SIST EN ISO 16484-5:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2026
Nadomešča:
SIST EN ISO 16484-5:2022
Sistemi za avtomatizacijo in regulacijo stavb - 5. del: Protokol za izmenjavo
podatkov (ISO 16484-5:2026)
Building automation and control systems (BACS) - Part 5: Data communication protocol
(ISO 16484-5:2026)
Systeme der Gebäudeautomation - Teil 5: Datenkommunikationsprotokoll (ISO 16484-
5:2026)
Systèmes de contrôle et d'automatisation des bâtiments (BACS) - Partie 5: Protocole de
communication de données (ISO 16484-5:2026)
Ta slovenski standard je istoveten z: EN ISO 16484-5:2026
ICS:
35.240.67 Uporabniške rešitve IT v IT applications in building
gradbeništvu and construction industry
97.120 Avtomatske krmilne naprave Automatic controls for
za dom household use
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 16484-5
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2026
EUROPÄISCHE NORM
ICS Supersedes EN ISO 16484-5:2022
English Version
Building automation and control systems (BACS) - Part 5:
Data communication protocol (ISO 16484-5:2026)
Systèmes d'automatisation et de gestion technique du Systeme der Gebäudeautomation - Teil 5:
bâtiment (BACS) - Partie 5: Protocole de Datenkommunikationsprotokoll (ISO 16484-5:2026)
communication de données (ISO 16484-5:2026)
This European Standard was approved by CEN on 26 July 2026.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16484-5:2026 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 16484-5:2026) has been prepared by Technical Committee ISO/TC 205
"Building environment design" in collaboration with Technical Committee CEN/TC 247 “Building
Automation, Controls and Building Management” the secretariat of which is held by SNV.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2027, and conflicting national standards
shall be withdrawn at the latest by February 2027.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 16484-5:2022.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 16484-5:2026 has been approved by CEN as EN ISO 16484-5:2026 without any
modification.
International
Standard
ISO 16484-5
Eighth edition
Building automation and control
2026-08
systems (BACS) —
Part 5:
Data communication protocol
Systèmes d'automatisation et de gestion technique du bâtiment
(BACS) —
Partie 5: Protocole de communication de données
Reference number
ISO 16484-5:2026(en) © ISO 2026
ISO 16484-5:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 16484-5:2026(en)
CONTENTS
Foreword . xi
FOREWORD . xii
1 PURPOSE . 1
2 SCOPE . 1
3 DEFINITIONS . 1
3.1 Terms Adopted from International Standards . 1
3.2 Terms Defined for this Standard . 2
3.3 Abbreviations and Acronyms Used in this Standard . 8
4 BACnet PROTOCOL ARCHITECTURE . 12
4.1 The BACnet Collapsed Architecture . 13
4.2 BACnet Network Topology . 15
4.3 Security . 16
5 THE APPLICATION LAYER . 17
5.1 The Application Layer Model . 17
5.2 Segmentation of BACnet Messages . 23
5.3 Transmission of BACnet APDUs . 24
5.4 Application Protocol State Machines . 28
5.5 Application Protocol Time Sequence Diagrams . 46
5.6 Application Layer Service Conventions . 55
6 THE NETWORK LAYER . 57
6.1 Network Layer Service Specification . 57
6.2 Network Layer PDU Structure . 59
6.3 Messages for Multiple Recipients . 65
6.4 Network Layer Protocol Messages . 65
6.5 Network Layer Procedures . 69
6.6 BACnet Routers . 71
6.7 Point-To-Point Half-Routers . 76
7 DATA LINK/PHYSICAL LAYERS: Ethernet (ISO 8802-3) LAN . 81
7.1 The Use of ISO 8802-2 Logical Link Control (LLC) . 81
7.2 Parameters Required by the LLC Primitives . 81
7.3 Parameters Required by the MAC Primitives . 81
7.4 Physical Media . 81
8 DATA LINK/PHYSICAL LAYERS: ARCNET (ATA 878.1) LAN . 82
8.1 The Use of ISO 8802-2 Logical Link Control (LLC) . 82
8.2 Parameters Required by the LLC Primitives . 82
8.3 Mapping the LLC Services to the ARCNET MAC Layer . 82
8.4 Parameters Required by the MAC Primitives . 82
8.5 Physical Media . 82
9 DATA LINK/PHYSICAL LAYERS: MULTIDROP SERIAL BUS/TOKEN PASSING (MS/TP) LAN . 84
9.1 Service Specification . 84
9.2 Physical Layer . 86
9.3 MS/TP Frame Format . 96
9.4 Overview of the MS/TP Network . 98
9.5 MS/TP Medium Access Control . 99
9.6 Cyclic Redundancy Check (CRC) . 120
9.7 Interfacing MS/TP LANs with Other BACnet LANs . 121
9.8 Responding BACnet User Processing of Messages from MS/TP . 121
9.9 Repeaters . 122
9.10 COBS (Consistent Overhead Byte Stuffing) Encoding . 123
9.11 Documenting MS/TP Node Design Choices. 127
10 DATA LINK/PHYSICAL LAYERS: POINT-TO-POINT (PTP) . 128
10.1 Overview . 128
10.2 Service Specification . 128
10.3 Point-to-Point Frame Format . 133
iii
ISO 16484-5:2026(en)
10.4 PTP Medium Access Control Protocol . 135
11 DATA LINK/PHYSICAL LAYERS: LonTalk (ISO/IEC 14908.1) LAN . 157
11.1 The Use of ISO 8802-2 Logical Link Control (LLC) . 157
11.2 Parameters Required by the LLC Primitives . 157
11.3 Mapping the LLC Services to the LonTalk Application Layer . 157
11.4 Parameters Required by the Application Layer Primitives . 157
11.5 Physical Media . 158
12 MODELING CONTROL DEVICES AS A COLLECTION OF OBJECTS . 160
12.1 Object Characteristics and Requirements . 160
12.2 Analog Input Object Type . 167
12.3 Analog Output Object Type . 174
12.4 Analog Value Object Type . 182
12.5 Averaging Object Type . 190
12.6 Binary Input Object Type . 194
12.7 Binary Output Object Type . 201
12.8 Binary Value Object Type . 210
12.9 Calendar Object Type . 218
12.10 Command Object Type . 221
12.11 Device Object Type . 228
12.12 Event Enrollment Object Type . 244
12.13 File Object Type . 253
12.14 Group Object Type . 257
12.15 Life Safety Point Object Type . 260
12.16 Life Safety Zone Object Type . 268
12.17 Loop Object Type . 276
12.18 Multi-state Input Object Type . 286
12.19 Multi-state Output Object Type . 292
12.20 Multi-state Value Object Type . 299
12.21 Notification Class Object Type . 307
12.22 Program Object Type . 313
12.23 Pulse Converter Object Type . 320
12.24 Schedule Object Type . 328
12.25 Trend Log Object Type . 336
12.26 Access Door Object Type . 347
12.27 Event Log Object Type . 357
12.28 Load Control Object Type . 365
12.29 Structured View Object Type . 376
12.30 Trend Log Multiple Object Type . 381
12.31 Access Point Object Type . 391
12.32 Access Zone Object Type . 409
12.33 Access User Object Type . 418
12.34 Access Rights Object Type . 422
12.35 Access Credential Object Type . 429
12.36 Credential Data Input Object Type . 439
12.37 CharacterString Value Object Type . 446
12.38 DateTime Value Object Type . 453
12.39 Large Analog Value Object Type . 459
12.40 BitString Value Object Type . 467
12.41 OctetString Value Object Type . 474
12.42 Time Value Object Type . 479
12.43 Integer Value Object Type . 485
12.44 Positive Integer Value Object Type . 493
12.45 Date Value Object Type . 501
12.46 DateTime Pattern Value Object Type . 507
12.47 Time Pattern Value Object Type . 513
12.48 Date Pattern Value Object Type . 519
12.49 Deleted Clause . 525
iv
ISO 16484-5:2026(en)
12.50 Global Group Object Type . 526
12.51 Notification Forwarder Object Type . 534
12.52 Alert Enrollment Object Type . 542
12.53 Channel Object Type . 546
12.54 Lighting Output Object Type . 557
12.55 Binary Lighting Output Object Type . 575
12.56 Network Port Object Type . 587
12.57 Timer Object Type . 629
12.58 Elevator Group Object Type . 642
12.59 Lift Object Type. 646
12.60 Escalator Object Type . 659
12.61 Accumulator Object Type . 667
12.62 Staging Object Type . 677
12.63 Audit Reporter Object Type . 688
12.64 Audit Log Object Type . 694
12.65 Color Object Type . 701
12.66 Color Temperature Object Type . 707
13 ALARM AND EVENT SERVICES . 714
13.1 Change of Value Reporting . 714
13.2 Event Reporting . 719
13.3 Event Algorithms . 732
13.4 Fault Algorithms . 764
13.5 AcknowledgeAlarm Service . 772
13.6 ConfirmedCOVNotification Service . 774
13.7 UnconfirmedCOVNotification Service . 776
13.8 ConfirmedEventNotification Service . 777
13.9 UnconfirmedEventNotification Service . 780
13.10 GetAlarmSummary Service . 783
13.11 GetEnrollmentSummary Service . 785
13.12 GetEventInformation Service . 788
13.13 LifeSafetyOperation Service . 791
13.14 SubscribeCOV Service . 793
13.15 SubscribeCOVProperty Service . 796
13.16 SubscribeCOVPropertyMultiple Service . 799
13.17 ConfirmedCOVNotificationMultiple Service . 805
13.18 UnconfirmedCOVNotificationMultiple Service . 808
13.19 AuditLogQuery . 810
13.20 ConfirmedAuditNotification . 814
13.21 UnconfirmedAuditNotification . 815
14 FILE ACCESS SERVICES . 816
14.1 AtomicReadFile Service . 816
14.2 AtomicWriteFile Service . 819
15 OBJECT ACCESS SERVICES . 822
15.1 AddListElement Service . 822
15.2 RemoveListElement Service . 825
15.3 CreateObject Service . 827
15.4 DeleteObject Service . 830
15.5 ReadProperty Service . 831
15.6 Deleted Clause . 833
15.7 ReadPropertyMultiple Service . 834
15.8 ReadRange Service . 837
15.9 WriteProperty Service . 845
15.10 WritePropertyMultiple Service . 848
15.11 WriteGroup Service . 851
16 REMOTE DEVICE MANAGEMENT SERVICES . 853
16.1 DeviceCommunicationControl Service . 853
16.2 ConfirmedPrivateTransfer Service . 855
v
ISO 16484-5:2026(en)
16.3 UnconfirmedPrivateTransfer Service . 857
16.4 ReinitializeDevice Service . 858
16.5 ConfirmedTextMessage Service . 860
16.6 UnconfirmedTextMessage Service . 862
16.7 TimeSynchronization Service . 863
16.8 UTCTimeSynchronization Service . 864
16.9 Who-Has and I-Have Services . 865
16.10 Who-Is and I-Am Services . 867
16.11 Who-Am-I and You-Are Services . 869
17 AUTHENTICATION AND AUTHORIZATION SERVICES . 872
17.1 Overview . 872
17.2 Trust of Intermediaries . 873
17.3 Authentication . 874
17.4 Authorization . 876
17.5 Conformance Requirements . 882
17.6 AuthRequest Service . 883
18 ERROR, REJECT, and ABORT CODES . 887
18.1 Error Class - DEVICE . 887
18.2 Error Class - OBJECT . 887
18.3 Error Class - PROPERTY . 888
18.4 Error Class - RESOURCES . 890
18.5 Error Class - SECURITY. 890
18.6 Error Class - SERVICES . 892
18.7 Error Class - COMMUNICATION . 893
18.8 Error Class - VT . 898
18.9 Reject Reason . 898
18.10 Abort Reason . 899
18.11 Confirmed Service Common Errors . 900
19 BACnet PROCEDURES . 901
19.1 Backup and Restore . 901
19.2 Command Prioritization . 906
19.3 Device Restart Procedure . 911
19.4 Determining Maximum Conveyable APDU . 912
19.5 Value Source Mechanism . 914
19.6 Audit Logging . 916
19.7 Unconfigured Device Discovery and Address Assignment . 927
19.8 Replacing Certificates in a BACnet/SC Network . 928
19.9 Device Address Proxying . 930
20 ENCODING BACnet PROTOCOL DATA UNITS . 934
20.1 Encoding the Fixed Part of BACnet APDUs . 935
20.2 Encoding the Variable Part of BACnet APDUs . 947
21 FORMAL DESCRIPTION OF APPLICATION PROTOCOL DATA UNITS . 963
21.1 APDU Definitions. 963
21.2 Confirmed Service Productions . 965
21.3 Unconfirmed Service Productions . 976
21.4 Error Productions . 980
21.5 Application Types . 992
21.6 Base Types . 994
22 CONFORMANCE AND INTEROPERABILITY . 1082
22.1 Conformance to BACnet. 1082
22.2 BACnet Interoperability . 1083
23 EXTENDING BACnet TO ACCOMMODATE VENDOR PROPRIETARY INFORMATION . 1085
23.1 Extending Enumeration Values . 1085
23.2 Using the PrivateTransfer Services to Invoke Non-Standardized Services . 1086
23.3 Adding Proprietary Properties to a Standardized Object . 1086
23.4 Adding Proprietary Object Types to BACnet . 1087
23.5 Restrictions on Extending BACnet . 1087
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ISO 16484-5:2026(en)
24 DELETED CLAUSE . 1088
25 REFERENCES . 1089
ANNEX A - PROTOCOL IMPLEMENTATION CONFORMANCE STATEMENT (NORMATIVE) . 1094
ANNEX B - GUIDE TO SPECIFYING BACnet DEVICES (INFORMATIVE) . 1098
ANNEX C - Removed .
...