ISO/IEC 14543-4-301:2020

Information technology - Home Electronic System (HES) architecture - Part 4-301: Application protocols for home air conditioners and controllers

Technologies de l'information — Architecture des systèmes électroniques domestiques (HES) — Partie 4-301: Protocoles d'application pour les climatiseurs à usage domestique et leurs dispositifs de commande

General Information

• Status: Published
• Publication Date: 07-Jul-2020
• ICS: 35.240.67 - IT applications in building and construction industry
• Technical Committee: ISO/IEC JTC 1/SC 25 - Interconnection of information technology equipment
• Drafting Committee: ISO/IEC JTC 1/SC 25 - Interconnection of information technology equipment
• Current Stage: 6060 - International Standard published
• Start Date: 08-Jul-2020
• Due Date: 22-Jun-2022
• Completion Date: 30-Jun-2020

Overview - ISO/IEC 14543-4-301:2020 (HES application protocols for air conditioners)

ISO/IEC 14543-4-301:2020 is an application‑layer standard in the Home Electronic System (HES) architecture series that defines application protocols for networked home air conditioners and controllers. It specifies message structures, command sequences and expected device/controller behaviours to ensure interoperability among products from different manufacturers. The protocol is implemented on top of the NECD model (Network Enhanced Control Device) defined in ISO/IEC 14543-4-3 and uses IP transport (UDP over IPv4/IPv6; TCP optional).

Key technical topics and requirements

• Application-layer message structure and sequences: Defines how controllers and air conditioners exchange requests, responses and status updates to ensure predictable interactions.
• NECD objects, services and properties: Specifies object types, service categories and object properties (including device object properties and object‑specific properties) used for HVAC control and monitoring.
• Operational procedures: Detailed behaviours for start‑up, periodical, occasional and fault‑state operations, including search, attribute discovery and status retrieval flows.
• Remote control and maintenance: Procedures and sequences for remote control, mobile access and remote appliance maintenance.
• Timing and reliability rules: Response wait timers, retransmission/resend rules, property counters and handling of continuous requests to maintain robust communication.
• Controller considerations: Guidance on controller restrictions, synchronization strategies, processing limits for object property counters, and fault‑status handling.

Practical applications and typical users

This standard is applicable to systems and services that integrate networked HVAC devices within smart homes and building automation, including:

• HVAC and smart‑home device manufacturers implementing interoperable air conditioners and controllers
• IoT solution developers and system integrators building multi‑vendor smart home systems
• Energy management platforms and remote maintenance/service providers that require standardized device control and diagnostics
• Certification bodies and test labs validating conformance to HES application protocols
• Use cases: energy management, comfort control, mobile access, remote appliance maintenance, home healthcare and home security integrations

Related standards

• ISO/IEC 14543-4-3 - Specifies the NECD application layer interface used as the basis for 14543-4-301.
• IEC 62394 - Defines control/diagnostic command lists (service diagnostic interface) referenced for object commands and terminology.
• ISO/IEC 14543-2-1 - Provides HES architecture background and device modularity concepts referenced by this part.

ISO/IEC 14543-4-301:2020 is Edition 1.0 (June 2020) and is part of the wider ISO/IEC 14543 HES series aimed at enabling interoperable, multi‑vendor home automation and HVAC control.

Standards Content (Sample)

ISO/IEC 14543-4-301
Edition 1.0 2020-06
INTERNATIONAL
STANDARD
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inside
Information technology – Home Electronic System (HES) architecture –
Part 4-301: Application protocols for home air conditioners and controllers

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ISO/IEC 14543-4-301
Edition 1.0 2020-06
INTERNATIONAL
STANDARD
colour
inside
Information technology – Home Electronic System (HES) architecture –

Part 4-301: Application protocols for home air conditioners and controllers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.240.67 ISBN 978-2-8322-8494-0

– 2 – ISO/IEC 14543-4-301:2020
 ISO/IEC 2020
CONTENTS
FOREWORD . 4
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 8
4 Conformance . 9
5 Connection configuration . 9
6 Application layer . 10
6.1 General . 10
6.2 NECD objects . 10
6.3 NECD services. 10
6.4 Object-specific NECD properties . 11
6.5 Application operation . 12
6.5.1 General . 12
6.5.2 Continuous requests . 12
6.5.3 Response wait timer value for controllers . 12
6.5.4 Resending a frame . 13
6.5.5 Processing object property counter . 13
6.5.6 Property values of write requests . 13
7 Normal operation . 13
7.1 General . 13
7.2 Start-up operation . 14
7.2.1 General . 14
7.2.2 Start-up processing of NECD nodes . 14
7.2.3 Search processing . 15
7.2.4 Obtaining NECD attribute information . 15
7.2.5 Obtaining home air conditioner attribute information . 16
7.3 Periodical operation . 16
7.4 Occasional operation . 16
7.4.1 General . 16
7.4.2 Obtaining home air conditioner status . 16
7.4.3 Controlling home air conditioners . 17
7.5 Operation during fault status . 18
8 Remote control . 19
8.1 General . 19
8.2 Processes to be carried out by controllers on remote control . 19
9 Considerations on controllers . 22
9.1 General . 22
9.2 Restrictions by home air conditioner implementations . 22
9.3 Processable number of object property counter. 24
9.4 Status synchronization by controllers (periodical operation) . 24
9.5 Reading fault status . 26

 ISO/IEC 2020
Annex A (informative) Terms and NECD frame format on ISO/IEC 14543-4-3 and
IEC 62394. 27
A.1 Terms correspondence between ISO/IEC 14543-4-3 and IEC 62394 . 27
A.2 NECD frame format . 27

Figure 1 – Relationship between IEC 62394, ISO/IEC 14543-4-3 and ISO/IEC 14543-4-301 . 5
Figure 2 – Connection configurations . 9
Figure 3 – Assumed network stack . 10
Figure 4 – Example of normal operation sequences . 14
Figure 5 – Example of sequence for obtaining NECD attribute information . 15
Figure 6 – Sequence to obtain status of home air conditioners. 17
Figure 7 – Sequence to control home air conditioners . 18
Figure 8 – Remote control . 19
Figure 9 – Remote control sequence (properties are written one by one) . 21
Figure 10 – Remote control sequence (properties are written in a batch) . 22
Figure 11 – Status synchronization flow by controllers . 25
Figure 12 – Obtaining detailed fault status information . 26
Figure A.1 – NECD frame format. 28

Table 1 – NECD objects . 10
Table 2 – NECD services . 11
Table 3 – NECD properties of device object (super class) . 11
Table 4 – NECD properties of device object . 12
Table 5 – Response wait timer value for controllers . 12
Table A.1 – Terms correspondence table between ISO/IEC 14543-4-3 and IEC 62394 . 27

– 4 – ISO/IEC 14543-4-301:2020
 ISO/IEC 2020
INFORMATION TECHNOLOGY –
HOME ELECTRONIC SYSTEM (HES) ARCHITECTURE –

Part 4-301: Application protocols for
home air conditioners and controllers

FOREWORD
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International Standard ISO/IEC 14543-4-301 has been prepared by subcommittee 25:
Interconnection of information technology equipment, of ISO/IEC joint technical committee 1:
Information technology.
The list of all currently available parts of the ISO/IEC 14543 series, under the general title
Information technology – Home Electronic System (HES) architecture, can be found on the IEC
and ISO websites.
The text of this document is based on the following documents:
CDV Report on voting
JTC1-SC25/2929/CDV JTC1-SC25/2952/RVC
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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 ISO/IEC 2020
INTRODUCTION
This document specifies the message structure, sequences and protocol of the application layer
for networked enhanced control devices used in the Home Electronic System. Some services
are targeted for communications between devices. Other services are exclusively reserved for
management purposes. Some services can be used for both management and run-time
communications. This document is applicable for energy management services, mobile access,
remote appliance maintenance services, home healthcare services, home security services and
comfort control.
This document specifies the detailed procedures and behaviours of both home air conditioners
and controllers at the application level communication based on ISO/IEC 14543-4-3.
Figure 1 shows the relationship between IEC 62394, ISO/IEC 14543-4-3 and
ISO/IEC 14543−4−301. The existing ISO/IEC 14543-4-3 specifies the message structure,
sequences and protocol for a general-purpose communication for use in network enhanced
control devices of the Home Electronic System (HES) Class 1. ISO/IEC 14543-4-3 provides the
common interfaces for the use-level process and the services such as energy management,
remote maintenance, and other services for easily building a system consisting of multi-vendor
devices and equipment. The existing IEC 62394 specifies the detailed lists of control commands
on NECD objects. Annex A shows terms and NECD frame format on ISO/IEC 14543-4-3 and
IEC 62394.
Since ISO/IEC 14543-4-3 is a general-purpose communication specification that applies to a
variety of devices, it does not focus on the detailed procedures and behaviours for each device
such as a home air conditioner.
In order to enhance interoperability, it is necessary to specify how to implement
ISO/IEC 14543−4-3 for each device or controller at the application level: command sequences,
timeout requirements, required combinations of acceptable commands, etc.

Figure 1 – Relationship between IEC 62394, ISO/IEC 14543-4-3 and ISO/IEC 14543-4-301

– 6 – ISO/IEC 14543-4-301:2020
 ISO/IEC 2020
INFORMATION TECHNOLOGY –
HOME ELECTRONIC SYSTEM (HES) ARCHITECTURE –

Part 4-301: Application protocols for
home air conditioners and controllers

1 Scope
This part of ISO/IEC 14543 specifies an application-layer protocol necessary for ensuring
interoperability among the products of various manufacturers regarding communications
between home air conditioners and controllers, using a protocol called network enhanced
communications device (NECD) as specified in ISO/IEC 14543-4-3. This protocol is based on
user datagram protocol (UDP) using IPv4 or IPv6 (TCP is optional).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
ISO/IEC 14543-2-1, Information technology – Home Electronic System (HES) architecture –
Part 2-1: Introduction and device modularity
ISO/IEC 14543-4-3, Information technology – Home Electronic System (HES) architecture –
Part 4-3: Application layer interface to lower communications layers for network enhanced
control devices of HES Class 1
IEC 62394, Service diagnostic interface for consumer electronics products and networks –
Implementation for ECHONET
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 14543-2-1 and
the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
controller
function embedded on unspecified devices for controlling home air conditioners
3.1.2
device object
NECD object other than node profile object
Note 1 to entry: In this document, it refers to home air conditioner object only.

 ISO/IEC 2020
3.1.3
home air conditioner
air conditioning device for home use including a communications interface that supports the
NECD protocol
Note 1 to entry: As used in this document, this term means the home air conditioner includes a communications
interface that supports the NECD protocol.
3.1.4
NECD communication middleware
middleware between the lower communication layers and the application layer that performs
communications processing according to the protocol specified in this document
3.1.5
NECD communication processing block
processing block for the communication middleware
Note 1 to entry: This block performs communications protocol processing to facilitate remote device control and
monitoring processing for application software, stores information for the above and controls various data on the
device as well as the status of other devices.
3.1.6
NECD data
NDATA
data region for a message exchanged by NECD communication middleware
3.1.7
NECD header
NHD
data containing the protocol type and message format for the NDATA section
3.1.8
NECD object
NOJ
model of information to be disclosed to the network from information owned by the NECD
communication processing block, or an access procedure model
Note 1 to entry: The information or control target owned by each device is specified as a property and the operating
method (setting, browsing) for this is specified as a service.
3.1.9
NECD property code
NPC
code value related to the NECD property
3.1.10
NECD protocol
communication protocol used in NECD communication specified in ISO/IEC 14543-4-3
3.1.11
NECD service
NSV
code value related to the NECD service
3.1.12
NECD frame
frame composed of NHD1, NHD2, TID and NDATA

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 ISO/IEC 2020
3.1.13
node profile
description of objects implemented in each node
3.1.14
property data counter
PDC
indication of the size of the NDT region
3.1.15
property value data
data value related to the NECD property code (NPC)
EXAMPLE Status notification or specific setting.
Note 1 to entry: Property value data is controlled by the NECD service (NSV).
3.1.16
remote control
control from outside the home
3.1.17
response wait timer
timer that counts the time from a controller request until a response from a targeted home air
conditioner
3.1.18
transaction ID
TID
parameter to link a sent request with a received response
3.1.19
super class
set of properties that are inherited to and implemented in all device object classes
3.2 Abbreviated terms
DNOJ destination NECD object
IP internet protocol
NDATA NECD DATA
NDT NECD Data
NECD network enhanced control device
NHD NECD header
NPC NECD property code
NSV NECD service
OPC processing object property counter
PDC property data counter
SNOJ source NECD object
TID transaction ID
UDP user datagram protocol
 ISO/IEC 2020
4 Conformance
Home air conditioners and controllers of HES Class 1 that claim conformance to this document
shall:
• send, receive and process sequences and procedures as specified in Clause 7;
• provide application services and properties specified in 6.2, 6.3 and 6.4 that may be needed
by home air conditioners and controllers for which the application is intended.
5 Connection configuration
This document specifies matters necessary for ensuring interoperability between the products
of different manufacturers in connection with application communication between home air
conditioners and controllers, using NECD protocol as an application protocol via
UDP(TCP)/IPv6 communications.
Figure 2 shows the configurations assumed under these specifications.

Figure 2 – Connection configurations
The upper illustration in Figure 2 shows the case where a single device object is installed in a
single node. The lower illustration shows the case where multiple device objects are installed
in a single node. The latter case occurs when multiple indoor units are attached to a single
outdoor unit, such as a so-called multi-split packaged air conditioner. In this case, there are
multiple home air conditioner class objects in a single home air conditioner node (i.e. at a single
IP address). Controllers are required to support nodes that configure multiple device objects in
a single node.
Controllers are required to be capable of handling multiple nodes and objects. The maximal
number of nodes and objects to be handled is implementation-dependent of the controllers. In
case that multiple controllers are connected to a single system, this would not be recognized
by the home air conditioner. In other words, the home air conditioner shall be controlled by the
last write request if multiple requests from multiple controllers arrive continuously before
responding.
Figure 3 shows the assumed network stack for operating NECD protocol in this document.
NECD protocol operation is assumed as an application protocol on UDP(TCP)/IPv6. Note that
TCP installation is optional. As a rule, the stack uses IPv6; however, IPv4 is allowed depending
on the market trends for migration from IPv4 to IPv6.

– 10 – ISO/IEC 14543-4-301:2020
 ISO/IEC 2020
a
Depends on transmission media using IPv6
Figure 3 – Assumed network stack
Connection processing specific to each lower layer communication medium that is necessary
in advance of the start of NECD communication is out of the scope of this document. In this
document, application communication using NECD protocol is described on the assumption that
connection processing specific to those communication media is complete.
6 Application layer
6.1 General
NECD protocol shall be used at the application layer. All nodes that conform to this document
shall support all mandatory functions specified in ISO/IEC 14543-4-3.
6.2 NECD objects
Home air conditioners and controllers shall have the NECD objects shown in Table 1.
Table 1 – NECD objects
NECD object Class group Class
Class name Instance code
code code
0x01 0x30 Home air conditioner 0x01 to 0x7F
Home air
conditioner
0x0E 0xF0 Node profile 0x01
0x05 0xFF Controller 0x01 to 0x7F
Controller
0x0E 0xF0 Node profile 0x01
NOTE Instance code 0x00 is designated to specify all instances of the same class in a node.
6.3 NECD services
Home air conditioners and controllers shall support the NECD services shown in Table 2.

 ISO/IEC 2020
Table 2 – NECD services
NSV code NECD service content Symbol
0x51 Property value write "response-not-possible" SetC_SNA
response
0x52 Property value read "response-not-possible" Get_SNA
response
0x61 Property value write request (response SetC
required)
0x62 Property value read request Get
0x71 Property value write response Set_Res
0x72 Property value read response Get_Res
0x73 Property value notification INF

NOTE NSV codes which are specified in ISO/IEC 14543-4-3 but are not shown in Table 2 (0x60, 0x63, 0x6E, 0x74,
0x7A, 0x7E, 0x50, 0x53, and 0x5E) are not subject to the certification tests based on this document.
6.4 Object-specific NECD properties
Home air conditioners shall install the NECD properties of device object shown in Table 3 and
Table 4. NECD properties of node profile object shall support at least mandatory properties.
Controllers shall send requests to the device object properties shown in Table 3 and Table 4.
In case a controller can control home air conditioners via a public network, its remote control
operations which set properties of home air conditioners shall include a write request
(SetC[0x61]) to Remote control setting property (0x93).
Table 3 – NECD properties of device object (super class)
Access rule
Announcement at
Property name NPC Remarks
status change
Get Set
I
...