IEC TR 62541-1:2020

IEC TR 62541-1 ®
Edition 3.0 2020-11
TECHNICAL
REPORT
colour
inside
OPC unified architecture –
Part 1: Overview and concepts
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IEC TR 62541-1 ®
Edition 3.0 2020-11
TECHNICAL
REPORT
colour
inside
OPC unified architecture –
Part 1: Overview and concepts
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.01 ISBN 978-2-8322-9076-7

– 2 – IEC TR 62541-1:2020 © IEC 2020
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 11
4 Structure of the OPC UA series . 12
4.1 Specification organization . 12
4.2 Core specification parts . 12
4.3 Access Type specification parts . 13
4.4 Utility specification parts . 13
5 Overview . 14
5.1 UA scope . 14
5.2 General . 14
5.3 Design goals . 14
5.4 Integrated models and services. 16
5.4.1 Security model . 16
5.4.2 Integrated AddressSpace model . 17
5.4.3 Integrated object model . 18
5.4.4 Integrated services . 18
5.5 Sessions . 18
6 Systems concepts . 19
6.1 Client Server Overview . 19
6.2 OPC UA Clients . 19
6.3 OPC UA Servers . 20
6.3.1 General . 20
6.3.2 Real objects . 20
6.3.3 Server application . 20
6.3.4 OPC UA AddressSpace . 21
6.3.5 Subscription entities . 21
6.3.6 OPC UA Service Interface . 21
6.3.7 Server to Server interactions . 22
6.4 Redundancy . 23
6.5 Publish-Subscribe . 23
6.6 Synergy of models . 24
7 Service Sets . 25
7.1 General . 25
7.2 Discovery Service Set . 25
7.3 SecureChannel Service Set . 25
7.4 Session Service Set . 26
7.5 NodeManagement Service Set . 26
7.6 View Service Set . 26
7.7 Query Service Set . 26
7.8 Attribute Service Set . 27
7.9 Method Service Set . 27
7.10 MonitoredItem Service Set . 27

7.11 Subscription Service Set . 28

Figure 1 – OPC UA specification organization . 12
Figure 2 – OPC UA target applications . 15
Figure 3 – OPC UA System architecture . 19
Figure 4 – OPC UA Client architecture . 19
Figure 5 – OPC UA Server architecture . 20
Figure 6 – Peer-to-peer interactions between Servers . 22
Figure 7 – Chained Server example . 23
Figure 8 – Integrated Client Server and PubSub models . 24
Figure 9 – SecureChannel and Session Services . 26

– 4 – IEC TR 62541-1:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPC UNIFIED ARCHITECTURE –
Part 1: Overview and concepts
FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 62541-1, which is a Technical Report, 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 of IEC TR 62541-1, published in
2016. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) added Subclauses 6.5 and 6.6 and other text throughout to include PubSub introduction;
b) added new transports and encodings to existing overview sections;
c) removed WS-SecureConversation example since this mapping has been deprecated;

d) improved the definition of Certificate.
The text of this Technical Report is based on the following documents:
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