EN IEC 62769-3:2021

SLOVENSKI STANDARD
01-julij-2021
Nadomešča:
SIST EN 62769-3:2015
Integracija procesne naprave (FDI) - 3. del: Strežnik FDI (IEC 62769-3:2021)
Field Device Integration (FDI) - Part 3: FDI Server (IEC 62769-3:2021)
Feldgeräteintegration (FDI) - Teil 3: FDI-Server (IEC 62769-3:2021)
Intégration des appareils de terrain (FDI) - Partie 3: Serveur FDI (IEC 62769-3:2021)
Ta slovenski standard je istoveten z: EN IEC 62769-3:2021
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 62769-3

NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2021
ICS 25.040.40; 35.100.05 Supersedes EN 62769-3:2015 and all of its amendments
and corrigenda (if any)
English Version
Field Device Integration (FDI) - Part 3: Server
(IEC 62769-3:2021)
Intégration des appareils de terrain (FDI) - Partie 3: Serveur Feldgeräteintegration (FDI) - Teil 3: FDI-Server
(IEC 62769-3:2021) (IEC 62769-3:2021)
This European Standard was approved by CENELEC on 2021-03-12. 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
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62769-3:2021 E

European foreword
The text of document 65E/760/FDIS, future edition 2 of IEC 62769-3, 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) 2021-12-12
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2024-03-12
document have to be withdrawn
This document supersedes EN 62769-3:2015 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.
Endorsement notice
The text of the International Standard IEC 62769-3:2021 was approved by CENELEC as a European
Standard without any modification.

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 61804 series Function blocks (FB) for process control EN IEC 61804 series
and electronic device description language
(EDDL)
IEC 61804-4 2020 Devices and integration in enterprise EN IEC 61804-4 2020
systems - Function blocks (FB) for process
control and electronic device description
language (EDDL) - Part 4: EDD
interpretation
IEC 62541-4 - OPC Unified Architecture - Part 4: Services EN IEC 62541-4 -
IEC 62541-7 - OPC unified architecture - Part 7: Profiles EN IEC 62541-7 -
IEC 62769-1 - Field Device Integration (FDI) - Part 1: EN 62769-1 -
Overview
IEC 62769-2 - Field Device Integration (FDI) - Part 2: FDI EN 62769-2 -
Client
IEC 62769-4 - Field Device Integration (FDI) - Part 4: FDI EN 62769-4 -
Packages
IEC 62769-5 - Field Device Integration (FDI) - Part 5: EN 62769-5 -
Information Model
IEC 62769-7 - Field Device Integration (FDI) - Part 7: EN 62769-7 -
Communication Devices
IEC 62769-3 ®
Edition 2.0 2021-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Field device integration (FDI) –

Part 3: Server
Intégration des appareils de terrain (FDI) –

Partie 3: Serveur
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 35.100.05 ISBN 978-2-8322-9310-2

– 2 – IEC 62769-3:2021 © IEC 2021
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, abbreviated terms and conventions . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 9
3.3 Conventions . 9
4 Overview . 9
5 Information Model . 10
5.1 General . 10
5.2 Online/Offline . 11
5.2.1 Overview . 11
5.2.2 Transfer to device . 11
5.2.3 Transfer from device . 11
5.3 Access privileges . 12
5.4 Private Parameters . 12
5.5 Locking . 12
5.6 EditContext . 13
5.6.1 Concept and usage model . 13
5.6.2 Services . 14
5.6.3 NodeIds . 15
5.6.4 Reading . 15
5.6.5 Writing . 15
5.6.6 Writing dominant and dependent Variables . 15
5.6.7 Actions (EDD METHODS) . 17
5.6.8 UIDs . 18
5.6.9 Synchronization . 18
5.7 Reading . 18
5.7.1 General . 18
5.7.2 Reading offline variables . 19
5.7.3 Reading online variables . 19
5.8 Writing . 20
5.8.1 General . 20
5.8.2 Write offline variables . 21
5.8.3 Writing online variables . 22
5.8.4 Writing to an EditContext . 24
5.9 Subscription . 25
5.9.1 General . 25
5.9.2 Subscription of offline variables . 25
5.9.3 Subscription of online variables . 26
5.10 Device topology . 28
5.10.1 General . 28
5.10.2 Connection Points . 28
5.10.3 Topology management . 29
5.10.4 Topology scanning . 32

IEC 62769-3:2021 © IEC 2021 – 3 –
5.10.5 Use of SCAN function . 33
5.10.6 Validation of defined topology . 34
5.11 User Interface Elements . 34
5.11.1 User Interface Descriptions. 34
5.11.2 User Interface Plug-ins . 35
5.12 Actions . 35
5.12.1 FDI Server – FDI Client interaction . 35
5.12.2 Action state machine . 38
5.12.3 Actions Proxies . 40
5.12.4 Actions, EDD Actions and Actions Proxies . 40
6 OPC UA services . 42
6.1 OPC UA profiles . 42
6.2 Service error information . 42
6.2.1 Overview . 42
6.2.2 OPC UA services and their response . 42
6.2.3 Mappings of EDDL response codes to OPC UA service response . 42
6.3 Parameter value update during write service request . 43
6.4 Localization . 44
6.5 Audit events . 44
7 Communication . 44
7.1 Notation . 44
7.2 General . 44
7.2.1 Concepts . 44
7.2.2 Terms . 47
7.3 Communication Service processing . 48
7.3.1 Communication Service invocation . 48
7.3.2 Analyze communication path . 48
7.3.3 Manage communication relations . 49
7.3.4 Communication service request mapping . 49
7.3.5 Communication service request propagation . 50
7.3.6 Communication error handling . 51
7.4 FDI Communication Server specific handling . 51
7.4.1 Discovery . 51
7.4.2 Information Model synchronization . 52
8 Parallel Execution within the FDI Server . 52
8.1 Motivation . 52
8.2 Internal structure of the EDD interpreter. 52
8.3 Rules for running an EDD entity . 53
Annex A (informative) FDI Server functional structure . 54
A.1 FDI functional elements . 54
A.2 FDI Server extension . 55
Annex B (informative) Access privileges and user roles . 57
B.1 User roles and usage case . 57
B.2 Private data usage . 58
Annex C (informative) Parallel execution within the FDI Server – Examples . 59
C.1 Simple example for a synchronous execution . 59
C.2 Example for a concurrent execution . 59
C.3 Deadlock detection in concurrent execution . 61

– 4 – IEC 62769-3:2021 © IEC 2021

Figure 1 – FDI architecture diagram . 8
Figure 2 – Locking services . 13
Figure 3 – EditContext models . 14
Figure 4 – Online EditContext state diagram for dominant and dependent Variables . 16
Figure 5 – Offline EditContext state diagram for dominant and dependent Variables . 17
Figure 6 – EditContext for EDD Methods . 17
Figure 7 – Offline variable read . 19
Figure 8 – Online variable read . 20
Figure 9 – Offline variable write immediate . 21
Figure 10 – Online variable write immediate . 23
Figure 11 – Write with EditContext . 24
Figure 12 – Offline variable subscription . 26
Figure 13 – Online variable subscription . 27
Figure 14 – Topology with Network objects (non-normative) . 28
Figure 15 – Add Device to topology . 30
Figure 16 – Remove device from topology . 31
Figure 17 – Scan topology . 32
Figure 18 – Action execution . 37
Figure 19 – Action state machine . 38
Figure 20 – System communication integration example . 45
Figure 21 – FDI Communication Server integration example . 46
Figure 22 – Gateway integration example . 47
Figure 23 – Message propagation example scenario . 50
Figure A.1 – Functional components of an FDI Server . 54
Figure A.2 – FDI Server extensions . 56
Figure B.1 – User roles and access privileges . 57
Figure C.1 – Synchronous execution of two triggers . 59
Figure C.2 – Concurrent execution of two triggers (step 1) . 59
Figure C.3 – Concurrent execution of two triggers (step 2) . 60
Figure C.4 – Concurrent execution of two triggers (step 3) . 60
Figure C.5 – Concurrent execution of two triggers (step 4) . 61
Figure C.6 – Concurrent execution of two triggers. 61

Table 1 – Action states . 38
Table 2 – Action state transitions . 39
Table 3 – EDD Action types and the EDD constructs that use them . 41
Table 4 – OPC UA severity bits and EDDL response codes TYPE . 43

IEC 62769-3:2021 © IEC 2021 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIELD DEVICE INTEGRATION (FDI) –

Part 3: Server
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
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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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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misinterpretation by any end user.
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 62769-3 has been prepared by subcommittee 65E: Devices and
integration in enterprise systems, of IEC technical committee 65: Industrial-process
measurement, control and automation.
This second edition cancels and replaces the first 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) modification of the edit context concept to harmonize the IEC 61804 and the IEC 62769
series.
– 6 – IEC 62769-3:2021 © IEC 2021
The text of this International Standard is based on the following documents:
FDIS Report on voting
65E/760/FDIS 65E/770/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.
A list of all parts in the IEC 62769 series, published under the general title Field Device
Integration (FDI), 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.
IEC 62769-3:2021 © IEC 2021 – 7 –
INTRODUCTION
The IEC 62769 series has the general title Field Device Integration (FDI) and the following
parts:
– Part 1: Overview
– Part 2: FDI Client
– Part 3: FDI Server
– Part 4: FDI Packages
– Part 5: FDI Information Model
– Part 6: FDI Technology Mapping
– Part 7: FDI Communication Devices
– Part 100: Profiles – Generic Protocol Extensions
– Part 101-1: Profiles – Foundation Fieldbus H1
– Part 101-2: Profiles – Foundation Fieldbus HSE
– Part 103-1: Profiles – PROFIBUS
– Part 103-4: Profiles – PROFINET
– Part 109-1: Profiles – HART and WirelessHART
– Part 115-2: Profiles – Protocol-specific Definitions for Modbus RTU
– Part 150-1: Profiles – ISA 100.11a

– 8 – IEC 62769-3:2021 © IEC 2021
FIELD DEVICE INTEGRATION (FDI) –

Part 3: Server
1 Scope
This part of IEC 62769 specifies the FDI Server. The overall FDI architecture is illustrated in
Figure 1. The architectural components that are within the scope of this document have been
highlighted in this figure.
Figure 1 – FDI architecture diagram
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 61804 (all parts), Function blocks (FB) for process control and electronic device
description language (EDDL)
IEC 62769-3:2021 © IEC 2021 – 9 –
IEC 61804-4:2020, Function blocks (FB) for process control and electronic device description
language (EDDL) – Part 4: EDD interpretation
IEC 62541-4, OPC unified architecture – Part 4: Services
IEC 62541-7, OPC unified architecture – Part 7: Profiles
IEC 62769-1, Field Device Integration (FDI) – Part 1: Overview
IEC 62769-2, Field Device Integration (FDI) – Part 2: FDI Client
IEC 62769-4, Field Device Integration (FDI) – Part 4: FDI Packages
IEC 62769-5, Field Device Integration (FDI) – Part 5: FDI Information Model
IEC 62769-7, Field Device Integration (FDI) – Part 7: Communication Devices
3 Terms, definitions, abbreviated terms and conventions
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62769-1 as well as
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
Actions Proxy
internal FDI Server entity that encapsulates all the EDD Methods specified in an EDD Action
definition
3.2 Abbreviated terms
For the purposes of this document, the abbreviated terms given in IEC 62769-1 apply.
3.3 Conventions
For the purposes of this document, the conventions given in IEC 62769-1 apply.
4 Overview
The structure for an FDI Server is shown in Figure 1.
FDI Servers that support connectivity with third-party FDI Clients shall support OPC UA. A
vendor can provide both an FDI Server and one or more FDI Clients. In this case, the FDI
Clients can communicate with the FDI Server through proprietary protocols.
An FDI Server communicates with devices via Native Communication (see 7.2.1) and/or
Communication Devices (see IEC 62769-7).

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An FDI Server provides information to FDI Clients through an Information Model (see
IEC 62769-5) as follows.
• The Information Model includes information about Device Types and Device Instances.
The information for a Device Instance includes offline data (engineering data), as well as
online data (values from the physical device).
• The Information Model is created using information from FDI Packages. However, not all
of the information in an FDI Package is reflected in the Information Model.
• Referential integrity of the Information Model is maintained using information from FDI
Packages.
• FDI Packages can contain Attachments that contain device manuals and protocol-specific
information (see IEC 62769-4). Those Attachments, including device manuals and
protocol-specific support files, are exposed via the Information Model.
• FDI Device Packages contain information about device types (see
IEC 62769-4). Each device type defined in a package is mapped to a distinct DeviceType
node in the Information Model.
• FDI Profile Packages are used to provide interaction with devices for which an FDI Device
Package does not exist (see IEC 62769-4).
• Multiple revisions of an FDI Package generate distinct DeviceType nodes in the
Information Model (see IEC 62769-4).
FDI Packages contain digital signatures that allow an FDI Server to authenticate their
contents (see IEC 62769-4). An FDI Server shall not use an FDI Package if the digital
signature provided by the FDI Package is invalid.
An FDI Server shall verify the FDI Technology Version (see IEC 62769-1) of any FDI Package
it uses to ensure the FDI Package is compatible with the FDI Server.
The resulting functional structure of an FDI server is described in Annex A.
5 Information Model
5.1 General
The FDI Server shall use the Device Definition of an FDI Package to maintain the Information
Model.
The Device Definition can contain conditional expressions. Conditional expressions are used
when a certain aspect of the Device Definition is not static but rather is dependent on the
state of the device. Whenever the online or offline values of a Device Instance are modified,
the FDI Server shall re-evaluate the relevant conditional expressions and modify the
Information Model accordingly.
The evaluation of conditional expressions can invalidate variables in the Information Model.
The FDI Server shall change the AccessLevel attribute of invalidated variables such that they
are neither readable nor writable and the status of these variables shall be set to bad. Read
and write service requests for invalidated variables shall return a failure.
The Device Definition can specify relationships between variables in a device. These
relationships can impact the value of variables in the Information Model.
The FDI Server shall generate DataChange Notifications to any FDI Clients that are
subscribing to Information Model elements that have changed.

IEC 62769-3:2021 © IEC 2021 – 11 –
FDI Packages provide Business Logic that is used by the FDI Server to maintain the integrity
of the Information Model. The Business Logic specified in an FDI Package can invoke builtin
functions that shall be implemented by the FDI Server. The builtin functions that shall be
implemented by the FDI Server are specified in IEC 61804-5.
5.2 Online/Offline
5.2.1 Overview
The Information Model maintained by the FDI Server contains online and offline values. The
online values reflect values in a physical component/device. The offline values reflect values
stored in a configuration database.
The offline values are updated through write service requests from an FDI Client or Business
Logic executed by the FDI Server. The offline values are not updated when the FDI Server
reads data from the device or writes data to the device.
The online values in the Information Model are not updated through write service requests.
Successful write service requests through the Information Model result in value changes in
the physical devices. The online values in the Information Model will then be updated as a
result of read service requests or subscriptions.
FDI Servers can provide a server-specific mechanism for creating Device Instances without
the presence of physical hardware. The FDI Server creates these instances using information
in FDI Packages. All read/write requests for online values for Device Instances with no
physical device shall return an error.
The transfer of information between the offline values and the physical device is supported
through the TransferToDevice and TransferFromDevice methods in the Information Model.
These Methods shall implement the download and upload procedures, respectively, as
specified in IEC 61804-4. When no implementation is provided based on IEC 61804-4, then
these Methods shall return Bad_NotSupported, as per IEC 62541-4.
The Device shall have been locked prior to invoking these methods, as specified in
IEC 62769-5.
5.2.2 Transfer to device
The TransferToDevice method shall implement the download procedure as specified in
IEC 61804-4. This transfers the offline values to the physical device.
As a general rule, the FDI Server should not change the Online variable node when writing a
value to the device. The Online variable node should be updated only in the process of read
operations or subscriptions. Notwithstanding, as specified in IEC 62769-5, the FDI Server will
reset any cached Value for the target Nodes in the Information Model so that they will be re-
read next time they are requested.
The status information returned for each variable included in the write service request is used
to compose the TransferResult, as specified in IEC 62769-5.
5.2.3 Transfer from device
The TransferFromDevice method shall implement the upload procedure as specified in
IEC 61804-4. This transfers the values from the physical device to the offline values.
If any read operations from the device fail during upload, the corresponding offline value shall
not be modified.
– 12 – IEC 62769-3:2021 © IEC 2021
The status information returned for each variable included in the read service request is used
to compose the TransferResult, as specified in IEC 62769-5.
5.3 Access privileges
Systems implement security and access policies based on a number of characteristics such
as user role and plant area. FDI Servers use these policies, along with information in FDI
Packages, to determine the access privileges granted to the user.
The elements of an FDI Package can be associated with one or more usage attributes. The
FDI Server uses these attributes to set the UserAccessLevel attribute of Variables and the
UserExecutable attribute of Methods. The usage attributes in an FDI Package are simply hints
to be used by the FDI Server, i.e., they may be disregarded or overridden by the FDI Server.
See also Annex B.
5.4 Private Parameters
The Parameters and Actions specified in an FDI Package may be declared private. Private
Parameters and Actions shall not be browsable; they shall only be accessible through
references from other elements of an FDI Package.
More specifically, the FDI Server shall support private Parameters and Actions as follows.
• The FDI Server shall create nodes in the Information Model for the private Parameters and
Actions.
• The FDI Server shall not include information about private Parameters and Actions in a
response to a Browse, BrowseNext, QueryFirst, or QueryNext service request.
• The FDI Server shall return the NodeIds of private Parameters and Actions when the
name of a private Parameter or Action is passed to TranslateBrowsePathsToNodeIds.
• The FDI Server shall process a read/write service request for a private Parameter in the
same way as it does for public (browsable) Parameters (see 5.7 and 5.8).
• The FDI Server shall execute private Actions in the same way as it does public
(browsable) Actions (see 5.12).
An example of private parameters is parameters that should only be modified through an
Action. These parameters should not be visible to FDI Clients to prevent direct access. FDI
Clients invoke Actions to access these private parameters.
5.5 Locking
The FDI Server provides locking services to grant FDI Clients exclusive access to Device and
Network elements in the Information Model. The locking services consist of a set of Methods
and status information. The methods, and their behavior, are specified in IEC 62769-5.
The following behavior shall be implemented by the FDI Server to support locks.
• Locking applies to both online and offline nodes.
• Once locked by one FDI Client, any attempt to write to a Parameter or to execute an
Action by another FDI Client shall be rejected.
• Locking is not required for read services.
• Parameters that are locked by one FDI Client can still be read by other FDI Clients, i.e.,
read requests on a Parameter that is locked are not rejected.
Internal use of the locking mechanism for maintaining the Information Model integrity is FDI
Server vendor-specific.
IEC 62769-3:2021 © IEC 2021 – 13 –
Figure 2 illustrates a locking sequence with multiple service invocations during the locked
state.
Figure 2 – Locking services
A service request that requires locking shall fail either partially or completely if no lock has
been acquired by the FDI Client via InitLock prior to requesting the service. The FDI Client
has to release the lock via ExitLock after all service requests have been completed.
A write operation will partially fail, i.e., it will return a status code for each variable in the set
of variables to be written since some may belong to devices that are locked and some to
devices that are not locked.
FDI Servers may queue InitLock requests until a service for which a lock has been created
completes and the lock has been released. However, such an optimization is not part of the
standard behavior required of an FDI Server.
5.6 EditContext
5.6.1 Concept and usage model
The FDI Server provides the EditContext model to interact with Clients during their editing
task. The concept is closely related to UIDs and fulfills the needs for Server-driven UI dialogs
based on EDDL rules.
An EditContext can be used to make changes to Variable Values visible to the Server without
applying them to the online or offline representation of a Device. The Server will apply
business logic associated to the edited Variable, which – in some cases – causes changes to
other Variable Values (e.g. if an engineering unit is changed) or the UID (e.g. a Variable
becomes invisible). Thus, the Client can use an EditContext to modify (edit) Parameters such
as engineering units, ranges and more, verify any side effects, and re-adjust the settings
before applying the changes.
An FDI Server may implement different EditContext strategies:
• A single EditContext instance for all dialogues of an FDI Client.
• Multiple EditContext instances.
• Hierarchical EditContext instances.

– 14 – IEC 62769-3:2021 © IEC 2021

Figure 3 – EditContext models
Figure 3 shows two possible Server strategies and how the Client can adapt. In the lower
scenario, the Server provides a single EditContext instance for all dialogs. Here, the Client
groups all dialogs and exposes a single set of buttons to Apply and Cancel, because it always
concerns all edits.
In the upper scenario, the Server provides multiple EditContext instances, one of them as
child of another one. Each instance can be addressed separately. If the changes in a child
instance are applied, they are transferred to the parent. If the changes in a root instance are
applied, they are transferred to the Device.
The parent-child dependencies are defined in IEC 61804-4:2020, Clause 8.
5.6.2 Services
A set of Services is provided to the FDI Client to maintain EditContext instances (see
IEC 62769-5 for a detailed description of these Services):
• GetContext – This Service is used to request an EditContext instance. The Client specifies
certain characteristics for the Server to decide which EditContext instance to return.
Depending on its internal strategy, the Server returns the same instance or new instances.
• RegisterNodes – The FDI Client has to register all Nodes of the Information Model that
shall be maintained in an EditContext. It is possible to register Nodes of the online and of
the offline representation of a Device. The result is new NodeIds that the Client shall use
when calling Services to read, write, subscribe to Variables or to invoke Actions.

IEC 62769-3:2021 © IEC 2021 – 15 –
• Apply – Transfer the modified (edited) Variable Values to the par
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