SIST EN IEC 62541-6:2026

SLOVENSKI STANDARD
01-maj-2026
Enotna arhitektura OPC - 6. del: Preslikave (IEC 62541-6:2025)
OPC unified architecture - Part 6: Mappings (IEC 62541-6:2025)
OPC Unified Architecture - Teil 6: Protokollabbildungen (IEC 62541-6:2025)
Architecture unifiée OPC - Partie 6: Mappings (IEC 62541-6:2025)
Ta slovenski standard je istoveten z: EN IEC 62541-6:2026
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 62541-6

NORME EUROPÉENNE
EUROPÄISCHE NORM February 2026
ICS 25.040.40; 35.100.05 Supersedes EN IEC 62541-6:2020
English Version
OPC unified architecture - Part 6: Mappings
(IEC 62541-6:2025)
Architecture unifiée OPC - Partie 6: Mappings OPC Unified Architecture - Teil 6: Protokollabbildungen
(IEC 62541-6:2025) (IEC 62541-6:2025)
This European Standard was approved by CENELEC on 2026-01-27. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62541-6:2026 E

European foreword
The text of document 65E/1063/CDV, future edition 4 of IEC 62541-6, prepared by SC 65E "Devices
and integration in enterprise systems" of IEC/TC 65 "Industrial-process measurement, control and
automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-02-28
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-02-28
document have to be withdrawn
This document supersedes EN IEC 62541-6:2020 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request addressed to CENELEC by the
European Commission. The Standing Committee of the EFTA States subsequently approves these
requests for its Member States.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 62541-6:2025 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 62541-21 NOTE Approved as EN IEC 62541-21 to be published
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 62541-1 - OPC Unified Architecture - Part 1: EN IEC 62541-1 -
Overview and concepts
IEC 62541-2 - OPC unified architecture - Part 2: Security EN IEC 62541-2 -
model
IEC 62541-3 - OPC Unified Architecture - Part 3: Address EN IEC 62541-3 -
Space Model
IEC 62541-4 - OPC unified architecture - Part 4: Services EN IEC 62541-4 -
IEC 62541-5 - OPC Unified architecture - Part 5: EN IEC 62541-5 -
Information Model
IEC 62541-7 - OPC Unified Architecture - Part 7: Profiles EN IEC 62541-7 -
IEC 62541-12 - OPC Unified Architecture - Part 13: EN IEC 62541-12 -
Aggregates
IEC 62541-18 - OPC unified architecture - Part 18: Role- EN IEC 62541-18 -
Based Security
ISO/IEC 60559, - Information technology - Microprocessor - -
IEEE 754 Systems - Floating-Point arithmetic
ISO 8601-1 - Date and time - Representations for - -
information interchange - Part 1: Basic
rules
ISO/IEC 7498-1 - Recommendation ITU-T X.200, Information - -
technology - Open Systems
Interconnection - Basic reference model:
The basic model
ISO/IEC 8825-1 - Recommendation ITU-T X.690, Information - -
technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules
(BER), Canonical Encoding Rules (CER)
and Distinguished Encoding Rules (DER)

Under preparation. Stage at the time of publication: FprEN IEC 62541-2:2025.
ISO/IEC 9594-8 - Recommendation ITU-T X.509, Information - -
technology - Open systems interconnection
– Part 8: The Directory: Public-key and
attribute certificate frameworks
IETF RFC 2104 - HMAC: Keyed-Hashing for Message - -
Authentication
IETF RFC 2818 - HTTP Over TLS - -
IETF RFC 3629 - UTF-8, a transformation format of ISO - -
IETF RFC 3986 - Uniform Resource Identifier (URI): Generic - -
Syntax
IETF RFC 4648 - The Base16, Base32, and Base64 Data - -
Encodings
IETF RFC 7230 - Hypertext Transfer Protocol (HTTP/1.1): - -
Message Syntax and Routing
IETF RFC 4514 - Lightweight Directory Access Protocol - -
(LDAP): String Representation of
Distinguished Names
IETF RFC 5234 - Augmented BNF for Syntax Specifications: - -
ABNF
IETF RFC 5280 - Internet X.509 Public Key Infrastructure - -
Certificate and Certificate Revocation List
(CRL) Profile
IETF RFC 5392 - OSPF Extensions in Support of Inter- - -
Autonomous System (AS) MPLS and
GMPLS Traffic Engineering
IETF RFC 5869 - HMAC-based Extract-and-Expand Key - -
Derivation Function
IETF RFC 5905 - Network Time Protocol Version 4: Protocol - -
and Algorithms Specification
IETF RFC 6455 - The WebSocket Protocol - -
IETF RFC 6749 - The OAuth 2.0 Authorization Framework - -
IETF RFC 6750 - The OAuth 2.0 Authorization Framework: - -
Bearer Token Usage
IETF RFC 6960 - X.509 - Internet Public Key Infrastructure - -
Online Certificate Status Protocol - OCSP
IETF RFC 7292 - PKCS #12: Personal Information Exchange - -
Syntax v1.1
IETF RFC 7523 - JSON Web Token (JWT) Profile for OAuth - -
2.0 Client Authentication and Authorization
Grants
IETF RFC 8017 - PKCS #1, RSA Cryptography - -
Specifications Version 2.2
IETF RFC 8141 - Uniform Resource Names (URNs) - -
IETF RFC 8259 - The JavaScript Object Notation (JSON) - -
Data Interchange Format
IETF RFC 8422 - Elliptic Curve Cryptography (ECC) Cipher - -
Suites for Transport Layer Security (TLS)
Versions 1.2 and Earlier
IETF RFC 8446 - The Transport Layer Security (TLS) - -
Protocol Version 1.3
FIPS 180-4 - Secure Hash Standard (SHS) - -
FIPS 197 - Advanced Encryption Standard (AES) - -
SOAP Part 1 - SOAP Version 1.2 Part 1: Messaging - -
Framework
WS Addressing - Web Services Addressing (WS- - -
Addressing)
XML Schema Part 2 - XML Schema Part 2: Datatypes - -
OpenID-Core - OpenID Connect Core 1.0 - -
OpenID-Discovery - OpenID Connect Discovery 1.0 - -
SemVer - Semantic Versioning 2.0.0 - -

IEC 62541-6 ®
Edition 4.0 2025-12
INTERNATIONAL
STANDARD
OPC unified architecture -
Part 6: Mappings
ICS 25.040.40; 35.100.05 ISBN 978-2-8327-0848-4

IEC 62541-6:2025-12(en)
IEC 62541-6:2025 © IEC 2025
CONTENTS
FOREWORD . 8
1 Scope . 10
2 Normative references . 10
3 Terms, definitions and abbreviated terms . 12
3.1 Terms and definitions. 12
3.2 Abbreviated terms . 14
4 Overview . 14
5 Data encoding . 15
5.1 General . 15
5.1.1 Overview . 15
5.1.2 Built-in Types . 15
5.1.3 Guid . 17
5.1.4 DateTime . 17
5.1.5 ByteString. 18
5.1.6 Number, Integer and UInteger . 18
5.1.7 Structures and Unions . 18
5.1.8 ExtensionObject . 18
5.1.9 Variant . 19
5.1.10 Decimal . 19
5.1.11 Null, Empty and Zero-Length Arrays . 20
5.1.12 QualifiedName, NodeId and ExpandedNodeId String Encoding . 20
5.1.13 Name Encoding Rules . 22
5.2 OPC UA Binary . 23
5.2.1 General . 23
5.2.2 Built-in Types . 23
5.2.3 Decimal . 34
5.2.4 Enumerations . 34
5.2.5 Arrays . 34
5.2.6 Structures . 35
5.2.7 Structures with optional fields . 38
5.2.8 Unions . 40
5.2.9 Messages . 43
5.3 OPC UA XML . 43
5.3.1 Built-in Types . 43
5.3.2 Decimal . 48
5.3.3 Enumerations . 49
5.3.4 Arrays . 49
5.3.5 Structures . 50
5.3.6 Structures with optional fields . 50
5.3.7 Unions . 51
5.3.8 Messages . 51
5.4 OPC UA JSON . 51
5.4.1 General . 51
5.4.2 Built-in Types . 52
5.4.3 Decimal . 57
5.4.4 Enumerations . 57
IEC 62541-6:2025 © IEC 2025
5.4.5 Arrays . 58
5.4.6 Structures . 58
5.4.7 Structures with optional fields . 59
5.4.8 Unions . 60
5.4.9 Messages . 61
6 Message SecurityProtocols . 61
6.1 Security handshake . 61
6.2 Certificates . 63
6.2.1 General . 63
6.2.2 Application Instance Certificate . 63
6.2.3 User Certificates . 65
6.2.4 Issuer (CA) Certificates . 65
6.2.5 Certificate Revocation List (CRL) . 65
6.2.6 Certificate Chains . 66
6.3 Time synchronization . 66
6.4 UTC and International Atomic Time (TAI) . 67
6.5 Issued User Identity Tokens . 67
6.5.1 Kerberos . 67
6.5.2 JSON Web Token (JWT) . 67
6.5.3 OAuth2 . 68
6.6 WS Secure Conversation . 70
6.7 OPC UA Secure Conversation . 70
6.7.1 Overview . 70
6.7.2 MessageChunk structure . 71
6.7.3 MessageChunks and error handling . 76
6.7.4 Establishing a SecureChannel . 77
6.7.5 Deriving keys . 78
6.7.6 Verifying Message Security . 80
6.8 Elliptic Curve Cryptography (ECC) . 81
6.8.1 Secure Channel Handshake . 81
6.8.2 UserIdentityToken Encryption . 85
6.8.3 ECC Encrypted Secret . 86
7 TransportProtocols . 87
7.1 OPC UA Connection Protocol . 87
7.1.1 Overview . 87
7.1.2 Message structure . 88
7.1.3 Establishing a connection . 91
7.1.4 Closing a connection . 93
7.1.5 Error handling . 94
7.2 OPC UA TCP . 96
7.3 SOAP/HTTP . 96
7.4 OPC UA HTTPS . 96
7.4.1 Overview . 96
7.4.2 Session-less Services . 98
7.4.3 XML Encoding . 98
7.4.4 OPC UA Binary Encoding . 99
7.4.5 JSON Encoding . 99
7.5 WebSockets . 100
7.5.1 Overview . 100
IEC 62541-6:2025 © IEC 2025
7.5.2 Protocol Mapping . 101
7.5.3 Security . 101
7.6 Well known addresses . 102
8 Normative Contracts . 102
8.1 OPC Binary Schema . 102
8.2 XML Schema and WSDL . 102
8.3 Information Model Schema. 102
8.4 Formal definition of UA Information Model . 103
8.5 Constants . 103
8.6 DataType encoding . 103
8.7 Security configuration . 103
Annex A (normative) Constants. 104
A.1 Attribute Ids . 104
A.2 Status Codes . 104
A.3 Numeric Node Ids . 105
A.4 Media Types . 106
Annex B (normative) OPC UA NodeSet . 107
Annex C (normative) Type declarations for the OPC UA native Mapping . 108
Annex D (normative) WSDL for the XML Mapping . 109
D.1 XML Schema . 109
D.2 WDSL Port Types . 109
D.3 WSDL Bindings . 109
Annex E (informative) Security settings management. 110
E.1 Overview . 110
E.2 SecuredApplication . 111
E.3 CertificateIdentifier . 115
E.4 CertificateStoreIdentifier . 116
E.5 CertificateList. 117
E.6 CertificateValidationOptions . 117
Annex F (normative) Information Model XML Schema . 119
F.1 Overview . 119
F.2 UANodeSet . 119
F.3 UANode . 122
F.4 Reference . 123
F.5 RolePermission . 124
F.6 UAType. 124
F.7 UAInstance . 124
F.8 UAVariable . 125
F.9 UAMethod . 125
F.10 TranslationType . 126
F.11 UADataType . 127
F.12 DataTypeDefinition . 128
F.13 DataTypeField . 129
F.14 Variant . 131
F.15 Example . 131
F.16 UANodeSetChanges . 133
F.17 NodesToAdd . 134
F.18 ReferencesToChange . 135
IEC 62541-6:2025 © IEC 2025
F.19 ReferenceToChange . 135
F.20 NodesToDelete . 135
F.21 NodeToDelete . 136
F.22 UANodeSetChangesStatus . 136
F.23 NodeSetStatusList . 137
F.24 NodeSetStatus . 137
Bibliography . 138

Figure 1 – The OPC UA Stack Overview . 15
Figure 2 – Encoding Integers in a binary stream . 24
Figure 3 – Encoding Floating Points in a binary stream . 24
Figure 4 – Encoding Strings in a binary stream . 25
Figure 5 – Encoding Guids in a binary stream . 26
Figure 6 – Encoding XmlElement in a binary stream . 26
Figure 7 – A String NodeId. 27
Figure 8 – A Two Byte NodeId . 28
Figure 9 – A Four Byte NodeId . 28
Figure 10 – Security handshake when Creating a Session . 61
Figure 11 – MessageChunk for Unauthenticated Encryption Algorithms . 71
Figure 12 – MessageChunk for Authenticated Encryption Algorithms . 71
Figure 13 – ECC Key Negotiation . 81
Figure 14 – Signing and Encryption with Authenticated Encryption . 84
Figure 15 – Signing and Encryption with Unauthenticated Encryption . 84
Figure 16 – ECC CreateSession/ActivateSession Handshake . 85
Figure 17 – OPC UA Connection Protocol Message structure . 88
Figure 18 – Client initiated OPC UA Connection Protocol connection . 92
Figure 19 – Server initiated OPC UA Connection Protocol connection. 92
Figure 20 – Closing a OPC UA Connection Protocol connection . 94
Figure 21 – Scenarios for the HTTPS Transport . 97
Figure 22 – Setting up Communication over a WebSocket . 100

Table 1 – Built-in Data Types . 16
Table 2 – Guid structure . 17
Table 3 – Layout of Decimal . 20
Table 4 – Additional ABNF Core Rules . 21
Table 5 – ABNF Description for a NodeId . 21
Table 6 – ABNF Description for a ExpandedNodeId . 22
Table 7 – ABNF Description for a QualifiedName . 22
Table 8 – Examples of XML Encoded Names . 23
Table 9 – Supported Floating Point Types. 24
Table 10 – NodeId components . 26
Table 11 – NodeId DataEncoding values . 27
Table 12 – Standard NodeId Binary DataEncoding . 27
Table 13 – Two Byte NodeId Binary DataEncoding . 28
IEC 62541-6:2025 © IEC 2025
Table 14 – Four Byte NodeId Binary DataEncoding . 28
Table 15 – ExpandedNodeId Binary DataEncoding . 29
Table 16 – DiagnosticInfo Binary DataEncoding . 30
Table 17 – QualifiedName Binary DataEncoding . 30
Table 18 – LocalizedText Binary DataEncoding . 31
Table 19 – Extension Object Binary DataEncoding . 32
Table 20 – Variant Binary DataEncoding . 33
Table 21 – Data Value Binary DataEncoding . 34
Table 22 – Inline Matrix DataEncoding . 35
Table 23 – Sample OPC UA Binary Encoded structure. 36
Table 24 – DataTypeDefinition for "Type1" from Sample . 37
Table 25 – DataTypeDefinition for "Type2" from Sample . 38
Table 26 – Sample OPC UA Binary Encoded Structure with optional fields . 39
Table 27 – Sample OPC UA Binary Encoded Structure . 41
Table 28 – XML Data Type Mappings for Integers . 43
Table 29 – XML Data Type Mappings for Floating Points . 43
Table 30 – Components of Enumeration . 49
Table 31 – JSON Object Definition for a NodeId . 53
Table 32 – JSON Object Definition for an ExpandedNodeId . 54
Table 33 – JSON Object Definition for a StatusCode . 54
Table 34 – JSON Object Definition for a DiagnosticInfo . 55
Table 35 – JSON Object Definition for a QualifiedName . 55
Table 36 – JSON Object Definition for a LocalizedText . 56
Table 37 – JSON Object Definition for an ExtensionObject . 56
Table 38 – JSON Object Definition for a Variant . 56
Table 39 – JSON Object Definition for a DataValue . 57
Table 40 – JSON Object Definition for a Decimal . 57
Table 41 – JSON Encoding Rules for Structures . 58
Table 42 – JSON Object Definition for a Structures with Optional Fields . 59
Table 43 – JSON Encoding Rules for Structures with Optional Fields . 59
Table 44 – JSON Object Definition for a Union . 60
Table 45 – SecurityPolicy . 62
Table 46 – Application Instance Certificate . 63
Table 47 – User Certificate . 65
Table 48 – Issuer Certificate . 65
Table 49 – Certificate Revocation List Extensions . 66
Table 50 – JWT UserTokenPolicy . 67
Table 51 – JWT IssuerEndpointUrl Definition . 68
Table 52 – Access Token Claims . 69
Table 53 – OPC UA Secure Conversation Message Header . 72
Table 54 – Asymmetric algorithm Security header . 73
Table 55 – Symmetric algorithm Security header . 74
Table 56 – Sequence header . 74
IEC 62541-6:2025 © IEC 2025
Table 57 – Message Footer for Unauthenticated Encryption Algorithms . 75
Table 58 – Message Footer for Authenticated Encryption Algorithms . 76
Table 59 – OPC UA Secure Conversation Message abort body. 76
Table 60 – OPC UA Secure Conversation OpenSecureChannel Service . 77
Table 61 – PRF inputs for RSA based SecurityPolicies . 79
Table 62 – Cryptography key generation parameters . 79
Table 63 – Deriving Client Keys from Keying Material . 83
Table 64 – Deriving Server Keys from Keying Material . 83
Table 65 – Creating a Mask for the Initialization Vector . 85
Table 66 – Additional Header Key Names . 86
Table 67 – Deriving Keys from Keying Material . 87
Table 68 – OPC UA Connection Protocol Message header . 88
Table 69 – OPC UA Connection Protocol Hello Message . 89
Table 70 – OPC UA Connection Protocol Acknowledge Message. 90
Table 71 – OPC UA Connection Protocol Error Message . 90
Table 72 – OPC UA Connection Protocol ReverseHello Message . 91
Table 73 – Client and Server Handshake during Reverse Connect . 93
Table 74 – OPC UA Connection Protocol error codes . 95
Table 75 – WebSocket Protocols Mappings . 101
Table 76 – Well known addresses for Local Discovery Servers . 102
Table A.1 – Identifiers assigned to Attributes . 104
Table A.2 – Media Types Assigned to OPC UA Document Formats . 106
Table E.1 – SecuredApplication . 112
Table E.2 – CertificateIdentifier . 115
Table E.3 – Structured directory store . 116
Table E.4 – CertificateStoreIdentifier . 117
Table E.5 – CertificateList . 117
Table E.6 – CertificateValidationOptions . 118
Table F.1 – UANodeSet . 120
Table F.2 – UANode . 122
Table F.3 – Reference . 123
Table F.4 – RolePermission . 124
Table F.5 – UANodeSet Type Nodes . 124
Table F.6 – UANodeSet Instance Nodes . 124
Table F.7 – UAInstance . 125
Table F.8 – UAVariable . 125
Table F.9 – UAMethod . 126
Table F.10 – TranslationType . 127
Table F.11 – UADataType . 128
Table F.12 – DataTypeDefinition . 129
Table F.13 – StructureType Enumeration Mapping . 129
Table F.14 – DataTypeField . 130
Table F.15 – UANodeSetChanges . 134
IEC 62541-6:2025 © IEC 2025
Table F.16 – NodesToAdd . 134
Table F.17 – ReferencesToChange . 135
Table F.18 – ReferencesToChange . 135
Table F.19 – NodesToDelete . 136
Table F.20 – ReferencesToChange . 136
Table F.21 – UANodeSetChangesStatus . 136
Table F.22 – NodeSetStatusList. 137
Table F.23 – NodeSetStatus . 137

IEC 62541-6:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPC unified architecture -
Part 6: Mappings
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publicatio
...