SIST EN IEC 62541-8:2020
(Main)OPC Unified Architecture - Part 8: Data Access (IEC 62541-8:2020)
OPC Unified Architecture - Part 8: Data Access (IEC 62541-8:2020)
This part of IEC 62541 is part of the overall OPC Unified Architecture (OPC UA) standard series
and defines the information model associated with Data Access (DA). It particularly includes
additional VariableTypes and complementary descriptions of the NodeClasses and Attributes
needed for Data Access, additional Properties, and other information and behaviour.
The complete address space model, including all NodeClasses and Attributes is specified in
IEC 62541-3. The services to detect and access data are specified in IEC 62541-4.
OPC Unified Architecture - Teil 8: Zugriff auf Automatisierungsdaten (IEC 62541-8:2020)
Architecture unifiée OPC - Partie 8: Accès aux données (IEC 62541-8:2020)
IEC 62541-8:2020 est disponible sous forme de IEC 62541-8:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
Le modèle d'espace d'adresses complet, comprenant toutes les NodeClasses et tous les Attributs, est spécifié dans l'IEC 62541-3. Les services de détection et d'accès aux données sont spécifiés dans l'IEC 62541-4.
Cette troisième édition annule et remplace la deuxième édition parue en 2015. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) ajout de nouveaux VariableTypes pour les AnalogItems;
b) ajout d'une annexe qui spécifie le mapping recommandé entre OPC UA DataAccess et OPC COM DataAccess;
c) modification de la description ambiguë de "Bad_NotConnected";
d) mise à jour de la description de EUInformation pour renvoyer à la dernière révision des unités CEFACT-ONU.
Enotna arhitektura OPC - 8. del: Dostop do podatkov (IEC 62541-8:2020)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN IEC 62541-8:2020
01-december-2020
Nadomešča:
SIST EN 62541-8:2015
Enotna arhitektura OPC - 8. del: Dostop do podatkov (IEC 62541-8:2020)
OPC Unified Architecture - Part 8: Data Access (IEC 62541-8:2020)
OPC Unified Architecture - Teil 8: Zugriff auf Automatisierungsdaten (IEC 62541-8:2020)
Architecture unifiée OPC - Partie 8: Accès aux données (IEC 62541-8:2020)
Ta slovenski standard je istoveten z: EN IEC 62541-8:2020
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
SIST EN IEC 62541-8:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN IEC 62541-8:2020
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SIST EN IEC 62541-8:2020
EUROPEAN STANDARD EN IEC 62541-8
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2020
ICS 35.100.05; 25.040.40 Supersedes EN 62541-8:2015 and all of its amendments
and corrigenda (if any)
English Version
OPC Unified Architecture - Part 8: Data Access
(IEC 62541-8:2020)
Architecture unifiée OPC - Partie 8: Accès aux données OPC Unified Architecture - Teil 8: Zugriff auf
(IEC 62541-8:2020) Automatisierungsdaten
(IEC 62541-8:2020)
This European Standard was approved by CENELEC on 2020-07-27. 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,
Turkey 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
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62541-8:2020 E
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SIST EN IEC 62541-8:2020
EN IEC 62541-8:2020 (E)
European foreword
The text of document 65E/708/FDIS, future edition 3 of IEC 62541-8, 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
EN IEC 62541-8:2020.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2021-04-27
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-07-27
document have to be withdrawn
This document supersedes EN 62541-8:2015 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 mandate given to CENELEC by the European Commission
and the European Free Trade Association.
Endorsement notice
The text of the International Standard IEC 62541-8:2020 was approved by CENELEC as a European
Standard without any modification.
2
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SIST EN IEC 62541-8:2020
EN IEC 62541-8:2020 (E)
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.cenelec.eu.
Publication Year Title EN/HD Year
IEC/TR 62541-1 - OPC unified architecture - Part 1: CLC/TR 62541-1 -
Overview and concepts
IEC 62541-3 - OPC Unified Architecture - Part 3: - -
Address Space Model
IEC 62541-4 - OPC Unified Architecture - Part 4: - -
Services
IEC 62541-5 - OPC Unified Architecture - Part 5: - -
Information Model
UNECE 20 - Codes for Units of Measure Used in - -
International Trade
3
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SIST EN IEC 62541-8:2020
IEC 62541-8
®
Edition 3.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
OPC unified architecture –
Part 8: Data access
Architecture unifiée OPC –
Partie 8: Accès aux données
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 35.100.05 ISBN 978-2-8322-8464-3
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN IEC 62541-8:2020
– 2 – IEC 62541-8:2020 © IEC 2020
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 8
4 Concepts . 8
5 Model . 9
5.1 General . 9
5.2 SemanticsChanged . 10
5.3 Variable Types . 10
5.3.1 DataItemType . 10
5.3.2 AnalogItem VariableTypes . 11
5.3.3 DiscreteItemType . 14
5.3.4 ArrayItemType . 17
5.4 Address Space model . 23
5.5 Attributes of DataItems . 24
5.6 DataTypes . 25
5.6.1 Overview . 25
5.6.2 Range . 25
5.6.3 EUInformation . 25
5.6.4 ComplexNumberType . 27
5.6.5 DoubleComplexNumberType . 27
5.6.6 AxisInformation . 28
5.6.7 AxisScaleEnumeration . 28
5.6.8 XVType . 29
6 Data Access specific usage of Services . 29
6.1 General . 29
6.2 PercentDeadband . 29
6.3 Data Access status codes . 30
6.3.1 Overview . 30
6.3.2 Operation level result codes . 30
6.3.3 LimitBits . 32
Annex A (informative) OPC COM DA to UA mapping . 33
A.1 Overview. 33
A.2 Security considerations . 33
A.3 COM UA wrapper for OPC DA Server . 33
A.3.1 Information Model mapping . 33
A.3.2 Data and error mapping . 37
A.3.3 Read data . 40
A.3.4 Write Data . 41
A.3.5 Subscriptions . 42
A.4 COM UA proxy for DA Client . 42
A.4.1 Guidelines . 42
A.4.2 Information Model and Address Space mapping . 42
A.4.3 Data and error mapping . 46
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IEC 62541-8:2020 © IEC 2020 – 3 –
A.4.4 Read data . 48
A.4.5 Write data . 49
A.4.6 Subscriptions . 49
Figure 1 – OPC DataItems are linked to automation data . 9
Figure 2 – DataItem VariableType hierarchy . 10
Figure 3 – Graphical view of a YArrayItem . 19
Figure 4 – Representation of DataItems in the AddressSpace . 24
Figure A.1 – Sample OPC UA Information Model for OPC DA . 34
Figure A.2 – OPC COM DA to OPC UA data and error mapping . 38
Figure A.3 – Status Code mapping. 39
Figure A.4 – Sample OPC DA mapping of OPC UA Information Model and Address
Space . 43
Figure A.5 – OPC UA to OPC DA data & error mapping . 46
Figure A.6 – OPC UA Status Code to OPC DA quality mapping . 48
Table 1 – DataItemType definition . 11
Table 2 – BaseAnalogType definition . 12
Table 3 – AnalogItemType definition . 13
Table 4 – AnalogUnitType definition . 13
Table 5 – AnalogUnitRangeType definition . 14
Table 6 – DiscreteItemType definition . 14
Table 7 – TwoStateDiscreteType definition . 15
Table 8 – MultiStateDiscreteType definition . 15
Table 9 – MultiStateValueDiscreteType definition . 16
Table 10 – ArrayItemType definition . 17
Table 11 – YArrayItemType definition . 18
Table 12 – YArrayItem item description. 20
Table 13 – XYArrayItemType definition . 20
Table 14 – ImageItemType definition . 21
Table 15 – CubeItemType definition . 22
Table 16 – NDimensionArrayItemType definition . 23
Table 17 – Range DataType structure . 25
Table 18 – Range definition . 25
Table 19 – EUInformation DataType structure . 25
Table 20 – EUInformation definition . 26
Table 21 – Examples from UNECE Recommendation N° 20 . 26
Table 22 – ComplexNumberType DataType structure . 27
Table 23 – ComplexNumberType definition . 27
Table 24 – DoubleComplexNumberType DataType structure . 27
Table 25 – DoubleComplexNumberType definition . 28
Table 26 – AxisInformation DataType structure . 28
Table 27 – AxisScaleEnumeration values. 28
Table 28 – AxisScaleEnumeration definition . 29
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Table 29 – XVType DataType structure . 29
Table 30 – XVType definition . 29
Table 31 – Operation level result codes for BAD data quality . 31
Table 32 – Operation level result codes for UNCERTAIN data quality . 31
Table 33 – Operation level result codes for GOOD data quality . 31
Table A.1 – OPC COM DA to OPC UA Properties mapping . 36
Table A.2 – DataTypes and mapping . 39
Table A.3 – Quality mapping . 40
Table A.4 – OPC DA Read error mapping . 41
Table A.5 – OPC DA Write error code mapping . 41
Table A.6 – DataTypes and Mapping . 47
Table A.7 – Quality mapping . 48
Table A.8 – OPC UA Read error mapping . 49
Table A.9 – OPC UA Write error code mapping . 49
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SIST EN IEC 62541-8:2020
IEC 62541-8:2020 © IEC 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPC UNIFIED ARCHITECTURE –
Part 8: Data access
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,
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62541-8 has been prepared by subcommittee 65E: Devices and
integration in enterprise systems, of IEC technical committee 65: Industrial-process
measurement, control and automation.
This third edition cancels and replaces the second edition published in 2015. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) added new VariableTypes for AnalogItems;
b) added an Annex that specifies a recommended mapping of OPC UA Dataccess to OPC
COM DataAccess;
c) changed the ambiguous description of "Bad_NotConnected";
d) updated description for EUInformation to refer to latest revision of UNCEFACT units.
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SIST EN IEC 62541-8:2020
– 6 – IEC 62541-8:2020 © IEC 2020
The text of this International Standard is based on the following documents:
FDIS Report on voting
65E/708/FDIS 65E/726/RVD
Full information on the voting for the approval of this International Standard 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.
Throughout this document and the other parts of the IEC 62541 series, certain document
conventions are used:
Italics are used to denote a defined term or definition that appears in the "Terms and definition"
clause in one of the parts of the IEC 62541 series.
Italics are also used to denote the name of a service input or output parameter or the name of
a structure or element of a structure that are usually defined in tables.
The italicized terms and names are, with a few exceptions, written in camel-case (the practice
of writing compound words or phrases in which the elements are joined without spaces, with
each element's initial letter capitalized within the compound). For example, the defined term is
AddressSpace instead of Address Space. This makes it easier to understand that there is a
single definition for AddressSpace, not separate definitions for Address and Space.
A list of all parts of the IEC 62541 series, published under the general title OPC Unified
Architecture, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
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SIST EN IEC 62541-8:2020
IEC 62541-8:2020 © IEC 2020 – 7 –
OPC UNIFIED ARCHITECTURE –
Part 8: Data access
1 Scope
This part of IEC 62541 is part of the overall OPC Unified Architecture (OPC UA) standard series
and defines the information model associated with Data Access (DA). It particularly includes
additional VariableTypes and complementary descriptions of the NodeClasses and Attributes
needed for Data Access, additional Properties, and other information and behaviour.
The complete address space model, including all NodeClasses and Attributes is specified in
IEC 62541-3. The services to detect and access data are specified in IEC 62541-4.
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.
IEC TR 62541-1, OPC Unified Architecture – Part 1: Overview and Concepts
IEC 62541-3, OPC Unified Architecture – Part 3: Address Space Model
IEC 62541-4, OPC Unified Architecture – Part 4: Services
IEC 62541-5, OPC Unified Architecture – Part 5: Information Model
UN/CEFACT: UNECE Recommendation N° 20, Codes for Units of Measure Used in
International Trade, available at
https://www.unece.org/cefact/codesfortrade/codes_index.html
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TR 62541-1,
IEC 62541-3, and IEC 62541-4 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
DataItem
link to arbitrary, live automation data, that is, data that represents currently valid information
Note 1 to entry: Examples of such data are
• device data (such as temperature sensors),
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• calculated data,
• status information (open/closed, moving),
• dynamically changing system data (such as stock quotes),
• diagnostic data.
3.1.2
AnalogItem
DataItem that represents continuously variable physical quantities (e.g. length, temperature),
in contrast to the digital representation of data in discrete items
Note 1 to entry: Typical examples are the values provided by temperature sensors or pressure sensors. OPC UA
defines a specific VariableType to identify an AnalogItem. Properties describe the possible ranges of AnalogItems.
3.1.3
DiscreteItem
DataItem that represents data that may take on only a certain number of possible values (e.g.
OPENING, OPEN, CLOSING, CLOSED)
Note 1 to entry: Specific VariableTypes are used to identify DiscreteItems with two states or with multiple states.
Properties specify the string values for these states.
3.1.4
ArrayItem
DataItem that represents continuously variable physical quantities and where each individual
data point consists of multiple values represented by an array (e.g., the spectral response of a
digital filter)
Note 1 to entry: Typical examples are the data provided by analyser devices. Specific VariableTypes are used to
identify ArrayItem variants.
3.1.5
EngineeringUnits
units of measurement for AnalogItems that represent continuously variable physical quantities
(e.g. length, mass, time, temperature)
Note 1 to entry: This standard defines Properties to inform about the unit used for the DataItem value and about
the highest and lowest value likely to be obtained in normal operation.
3.2 Abbreviated terms
DA data access
EU engineering unit
UA Unified Architecture
4 Concepts
Data Access deals with the representation and use of automation data in Servers.
Automation data can be located inside the Server or on I/O cards directly connected to the
Server. It can also be located in sub-servers or on other devices such as controllers and
input/output modules, connected by serial links via field buses or other communication links.
OPC UA Data Access Servers provide one or more OPC UA Data Access Clients with
transparent access to their automation data.
The links to automation data instances are called DataItems. The categories of automation data
are
...
SLOVENSKI STANDARD
oSIST prEN IEC 62541-8:2018
01-november-2018
Enotna arhitektura OPC - 8. del: Dostop do podatkov
OPC Unified Architecture - Part 8: Data Access
Architecture unifiée OPC - Partie 8: Accès aux données
Ta slovenski standard je istoveten z: prEN IEC 62541-8:2018
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
oSIST prEN IEC 62541-8:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN IEC 62541-8:2018
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oSIST prEN IEC 62541-8:2018
65E/609/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 62541-8 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2018-08-17 2018-11-09
SUPERSEDES DOCUMENTS:
65E/557/RR
IEC SC 65E : DEVICES AND INTEGRATION IN ENTERPRISE SYSTEMS
SECRETARIAT: SECRETARY:
United States of America Mr Donald (Bob) Lattimer
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which
they are aware and to provide supporting documentation.
TITLE:
OPC Unified Architecture - Part 8: Data Access
PROPOSED STABILITY DATE: 2021
NOTE FROM TC/SC OFFICERS:
Copyright © 2018 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.
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oSIST prEN IEC 62541-8:2018
IEC CDV 62541-8 © IEC 2017 - 2 - 65E/609/CDV
CONTENTS
FIGURES . 4
TABLES . 5
FOREWORD . 2
1 Scope . 9
2 Normative references . 9
3 Terms, definitions and abbreviations . 9
3.1 Terms and definitions . 9
3.2 Abbreviations and symbols . 10
4 Concepts . 10
5 Model . 11
5.1 General . 11
5.2 SemanticsChanged . 12
5.3 Variable Types . 12
5.3.1 DataItemType . 12
5.3.2 AnalogItemType . Error! Bookmark not defined.
5.3.3 DiscreteItemType . 14
5.3.4 ArrayItemType . 17
5.4 Address Space model . 22
5.5 Attributes of DataItems . 23
5.6 DataTypes . 23
5.6.1 Overview . 23
5.6.2 Range . 23
5.6.3 EUInformation . 24
5.6.4 ComplexNumberType . 25
5.6.5 DoubleComplexNumberType . 25
5.6.6 AxisInformation . 26
5.6.7 AxisScaleEnumeration . 26
5.6.8 XVType . 26
6 Data Access specific usage of Services . 27
6.1 General . 27
6.2 PercentDeadband. 27
6.3 Data Access status codes . 27
6.3.1 Overview . 27
6.3.2 Operation level result codes . 28
6.3.3 LimitBits . 29
Annex A (informative): OPC COM DA to UA Mapping . 30
A.1 Introduction . 30
A.2 Security Considerations . 30
A.3 COM UA wrapper for OPC DA Server . 31
A.3.1 Information Model mapping . 31
A.3.2 Data and error mapping . 34
A.3.3 Read data . 37
A.3.4 Write Data . 38
A.3.5 Subscriptions . 38
A.4 COM UA proxy for DA Client . 39
A.4.1 Guidelines . 39
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65E/609/CDV - 3 - IEC CDV 62541-8 © IEC 2017
A.4.2 Information Model and Address Space mapping . 39
A.4.3 Data and error mapping . 43
A.4.4 Read data . 45
A.4.5 Write data . 46
A.4.6 Subscriptions . 46
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oSIST prEN IEC 62541-8:2018
IEC CDV 62541-8 © IEC 2017 - 4 - 65E/609/CDV
FIGURES
Figure 1 – OPC DataItems are linked to automation data . 11
Figure 2 – DataItem VariableType hierarchy . 12
Figure 3 – Graphical view of a YArrayItem . 19
Figure 4 – Representation of DataItems in the AddressSpace . 22
Figure A.1 – Sample OPC UA Information Model for OPC DA . 31
Figure A.2 – OPC COM DA to OPC UA data & error mapping . 35
Figure A.3 - Status Code mapping . 36
Figure A.4 – Sample OPC DA mapping of OPC UA Information Model and Address Space . 40
Figure A.5 – OPC UA to OPC DA data & error mapping . 43
Figure A.6 – OPC UA Status Code to OPC DA quality mapping . 45
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oSIST prEN IEC 62541-8:2018
65E/609/CDV - 5 - IEC CDV 62541-8 © IEC 2017
TABLES
Table 1 – DataItemType definition . 12
Table 2 – AnalogItemType definition . 13
Table 3 – DiscreteItemType definition . 15
Table 4 – TwoStateDiscreteType definition . 15
Table 5 – MultiStateDiscreteType definition . 16
Table 6 – MultiStateValueDiscreteType definition . 16
Table 7 – ArrayItemType definition . 17
Table 8 – YArrayItemType definition . 18
Table 9 – YArrayItem item description . 19
Table 10 – XYArrayItemType definition . 20
Table 11 – ImageItemType definition . 20
Table 12 – CubeItemType definition . 21
Table 13 – NDimensionArrayItemType definition . 22
Table 14 – Range DataType structure . 23
Table 15 – Range definition . 23
Table 16 – EUInformation DataType structure . 24
Table 17 – EUInformation definition . 24
Table 18 – Examples from the UNECE Recommendation . 24
Table 19 – ComplexNumberType DataType structure . 25
Table 20 – ComplexNumberType definition . 25
Table 21 – DoubleComplexNumberType DataType structure . 25
Table 22 – DoubleComplexNumberType definition . 26
Table 23 – AxisInformation DataType structure . 26
Table 24 – AxisScaleEnumeration values . 26
Table 25 – AxisScaleEnumeration definition . 26
Table 26 – XVType DataType structure . 27
Table 27 – XVType definition . 27
Table 28 – Operation level result codes for BAD data quality . 29
Table 29 – Operation level result codes for UNCERTAIN data quality . 29
Table 30 – Operation level result codes for GOOD data quality . 29
Table A.1 – OPC COM DA to OPC UA Properties mapping . 33
Table A.2 – DataTypes and mapping . 36
Table A.3 – Quality mapping . 37
Table A.4 – OPC DA Read error mapping. 38
Table A.5 – OPC DA Write error code mapping . 38
Table A.6 – DataTypes and Mapping . 44
Table A.7 – Quality mapping . 45
Table A.8 – OPC UA Read error mapping. 46
Table A.9 – OPC UA Write error code mapping . 46
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IEC CDV 62541-8 © IEC 2017 - 2 - 65E/609/CDV
1 INTERNATIONAL ELECTROTECHNICAL COMMISSION
2 ____________
3
4 OPC UNIFIED ARCHITECTURE –
5
6 Part 8: Data access
7
8 FOREWORD
9 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all
10 national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-
11 operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition
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14 to technical committees; any IEC National Committee interested in the subject dealt with may participate in this
15 preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate
16 in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance
17 with conditions determined by agreement between the two organizations.
18 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
19 consensus of opinion on the relevant subjects since each technical committee has representation from all interested
20 IEC National Committees.
21 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees
22 in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate,
23 IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user.
24 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently
25 to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication
26 and the corresponding national or regional publication shall be clearly indicated in the latter.
27 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
28 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services
29 carried out by independent certification bodies.
30 6) All users should ensure that they have the latest edition of this publication.
31 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members
32 of its technical committees and IEC National Committees for any personal injury, property damage or other damage of
33 any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the
34 publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
35 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
36 indispensable for the correct application of this publication.
37 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
38 rights. IEC shall not be held responsible for identifying any or all such patent rights.
39 The main task of IEC technical committees is to prepare International Standards. However, a
40 technical committee may propose the publication of a technical report when it has collected data of a
41 different kind from that which is normally published as an International Standard, for example "state
42 of the art".
43 IEC 62541-8 has been prepared by subcommittee 65E: Devices and integration in enterprise
44 systems, of IEC technical committee 65: Industrial-process measurement, control and automation.
45 The text of this technical report is based on the following documents:
Enquiry draft Report on voting
65E/XX/DTR 65E/XX/RVC
46
47 Full information on the voting for the approval of this technical report can be found in the report on
48 voting indicated in the above table.
49 This third edition cancels and replaces the second edition of IEC 62541, published in 2015.
50 This edition includes the following significant technical changes with respect to the previous edition:
51 a) Added new VariableTypes for AnalogItems
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52 b) Added an Annex that specifies a recommended mapping of OPC UA Dataccess to OPC COM
53 DataAccess.
54 c) Changed the ambiguous description of “Bad_NotConnected”.
55 d) Updated description for EUInformation to refer to latest revision of UNCEFACT units.
56
57 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
58 Throughout this document and the referenced other Parts of the series, certain document
59 conventions are used:
60 Italics are used to denote a defined term or definition that appears in the “Terms and definition”
61 clause in one of the parts of the series.
62 Italics are also used to denote the name of a service input or output parameter or the name of a
63 structure or element of a structure that are usually defined in tables.
64 The italicized terms and names are also often written in camel-case (the practice of writing
65 compound words or phrases in which the elements are joined without spaces, with each element's
66 initial letter capitalized within the compound). For example the defined term is AddressSpace instead
67 of Address Space. This makes it easier to understand that there is a single definition for
68 AddressSpace, not separate definitions for Address and Space.
69 A list of all parts of the IEC 62541 series, published under the general title OPC Unified Architecture,
70 can be found on the IEC website.
71 The committee has decided that the contents of this publication will remain unchanged until the
72 stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the
73 specific publication. At this date, the publication will be
74 • reconfirmed,
75 • withdrawn,
76 • replaced by a revised edition, or
77 • amended.
78
79 The National Committees are requested to note that for this publication the stability date is 2021.
80 THIS TEXT IS INCLUDED FOR THE INFORMATION OF THE NATIONAL COMMITTEES AND WILL BE DELETED AT
81 THE PUBLICATION STAGE.
82 A bilingual version of this publication may be issued at a later date.
83
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
84
85
86
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87 OPC UNIFIED ARCHITECTURE –
88
89 Part 8: Data Access
90
91
92
93 1 Scope
94 This specification is part of the overall OPC Unified Architecture (OPC UA) standard series
95 and defines the information model associated with Data Access (DA). It particularly includes
96 additional VariableTypes and complementary descriptions of the NodeClasses and Attributes
97 needed for Data Access, additional Properties, and other information and behaviour.
98 The complete address space model, including all NodeClasses and Attributes is specified in
99 IEC 62541-3. The services to detect and access data are specified in IEC 62541-4.
100 2 Normative references
101 The following referenced documents are indispensable for the application of this document.
102 For dated references, only the edition cited applies. For undated references, the latest edition
103 of the referenced document (including any amendments) applies.
104 IEC TR 62541-1, OPC Unified Architecture – Part 1: Overview and Concepts
105 IEC 62541-3, OPC unified architecture – Part 3: Address Space Model
106 IEC 62541-4, OPC unified architecture – Part 4: Services
107 IEC 62541-5, OPC unified architecture – Part 5: Information Model
108 UN/CEFACT: UNECE Recommendation N° 20, Codes for Units of Measure Used in
109 International Trade, available at http://www.unece.org/tradewelcome/un-centre-for-trade-
110 facilitation-and-e-business-uncefact/outputs/cefactrecommendationsrec-index/list-of-trade-
111 facilitation-recommendations-n-16-to-20.html
112 3 Terms, definitions and abbreviations
113 3.1 Terms and definitions
114 For the purposes of this document, the terms and definitions given in IEC TR 62541-1,
115 IEC 62541-3, and IEC 62541-4 as well as the following apply.
116 3.1.1
117 DataItem
118 link to arbitrary, live automation data, that is, data that represents currently valid information
119 Note 1 to entry: Examples of such data are
120 • device data (such as temperature sensors),
121 • calculated data,
122 • status information (open/closed, moving),
123 • dynamically-changing system data (such as stock quotes),
124 • diagnostic data.
125 3.1.2
126 AnalogItem
127 DataItems that represent continuously-variable physical quantities (e.g., length, temperature),
128 in contrast to the digital representation of data in discrete items
129 Note 1 to entry: Typical examples are the values provided by temperature sensors or pressure sensors. OPC UA
130 defines a specific VariableType to identify an AnalogItem. Properties describe the possible ranges of AnalogItems.
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131 3.1.3
132 DiscreteItem
133 DataItems that represent data that may take on only a certain number of possible values (e.g.,
134 OPENING, OPEN, CLOSING, CLOSED)
135 Note 1 to entry: Specific VariableTypes are used to identify DiscreteItems with two states or with multiple states.
136 Properties specify the string values for these states.
137 3.1.4
138 ArrayItem
139 DataItems that represent continuously-variable physical quantities and where each individual
140 data point consists of multiple values represented by an array (e.g., the spectral response of
141 a digital filter)
142 Note 1 to entry: Typical examples are the data provided by analyser devices. Specific VariableTypes are used to
143 identify ArrayItem variants.
144 3.1.5
145 EngineeringUnits
146 units of measurement for AnalogItems that represent continuously-variable physical quantities
147 (e.g., length, mass, time, temperature)
148 Note 1 to entry: This standard defines Properties to inform about the unit used for the DataItem value and about
149 the highest and lowest value likely to be obtained in normal operation.
150 3.2 Abbreviations and symbols
151 DA Data Access
152 EU Engineering Unit
153 UA Unified Architecture
154 4 Concepts
155 Data Access deals with the representation and use of automation data in Servers.
156 Automation data can be located inside the Server or on I/O cards directly connected to the
157 Server. It can also be located in sub-servers or on other devices such as controllers and
158 input/output modules, connected by serial links via field buses or other communication links.
159 OPC UA Data Access Servers provide one or more OPC UA Data Access Clients with
160 transparent access to their automation data.
161 The links to automation data instances are called DataItems. Which categories of automation
162 data are provided is completely vendor-specific. Figure 1 illustrates how the AddressSpace of
163 a Server might consist of a broad range of different DataItems.
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164
165 Figure 1 – OPC DataItems are linked to automation data
166 Clients may read or write DataItems, or monitor them for value changes. The Services needed
167 for these operations are specified in IEC 62541-4. Changes are defined as a change in status
168 (quality) or a change in value that exceeds a client-defined range called a Deadband. To
169 detect the value change, the difference between the current value and the last reported value
170 is compared to the Deadband.
171 5 Model
172 5.1 General
173 The DataAccess model extends the variable model by defining VariableTypes. The
174 DataItemType is the base type. ArrayItemType, AnalogItemType and DiscreteItemType (and
175 its TwoState and MultiState subtypes) are specializations. See Figure 2. Each of these
176 VariableTypes can be further extended to form domain or server specific DataItems.
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BaseDataVariableType
Defined in
[UA Part 5]
Type DataItemType
DiscreteItemType
ArrayItem
EUItemType
Type
AnalogItem
TwoStateDiscreteType
AnalogUnit
Type
ItemType
MultiState MultiStateValue
DiscreteType DiscreteType
177
178
179 Figure 2 – DataItem VariableType hierarchy
180 5.2 SemanticsChanged
181 The StatusCode also contains an informational bit called SemanticsChanged.
182 Servers that implement Data Access shall set this Bit in notifications if certain Properties
183 defined in this standard change. The corresponding Properties are specified individually for
184 each VariableType.
185 Clients that use any of these Properties should re-read them before they process the data
186 value.
187 5.3 Variable Types
188 5.3.1 DataItemType
189 This VariableType defines the general characteristics of a DataItem. All other DataItem Types
190 derive from it. The DataItemType derives from the BaseDataVariableType and therefore
191 shares the variable model as described in IEC 62541-3 and IEC 62541-5. It is formally defined
192 in Table 1.
193 Table 1 – DataItemType definition
Attribute Value
BrowseName DataItemType
IsAbstract False
ValueRank −2 (−2 = ‘Any’)
DataType BaseDataType
References NodeClass BrowseName DataType TypeDefinition ModellingRule
Subtype of the BaseDataVariableType defined in IEC 62541-5; i.e the Properties of that type are inherited.
HasSubtype VariableType AnalogItemType Defined in 5.3.2
HasSubtype VariableType DiscreteItemType Defined in 5.3.3
HasSubtype VariableType ArrayItemType Defined in 5.3.4
HasProperty Variable Definition String PropertyType Optional
HasProperty Variable ValuePrecision Double PropertyType Optional
194
195 De
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