SIST EN IEC 62541-24:2026

OPC unified architecture - Part 24: Scheduler (IEC 62541-24:2026)

IEC 62541-24:2026 specifies an OPC UA information model to expose information, at what dates and times specific actions are executed by the OPC UA Server. Those schedules can optionally also be manipulated via the information model.
The schedule defines on which dates they are active, and can also reference global calendars representing specific dates, for example public holidays. In addition, the schedule defines times and actions that will be executed at that time. The model defines writing Variables and calling Methods but can be extended to other actions as well.
The NamespaceUri for all NodeIds defined in this document is defined in Annex A.

OPC Unified Architecture – Teil 24: Scheduler (IEC 62541-24:2026)

Architecture unifiée OPC - Partie 24: Ordonnanceur (IEC 62541-24:2026)

IEC 62541-24:2026 spécifie un Modèle d'information OPC UA pour présenter des informations, aux dates et heures auxquelles des actions spécifiques sont exécutées par le Serveur OPC UA. Ces programmes peuvent aussi être éventuellement manipulés au travers du modèle d'information.
Le programme définit les dates auxquelles les actions ont lieu, et peut également référencer des calendriers globaux indiquant des dates spécifiques, comme les jours fériés. De plus, le programme définit les heures et les actions exécutées au moment indiqué. Le modèle définit l'écriture de Variables et l'appel de Méthodes, mais peut également être étendu à d'autres actions.
Le NamespaceUri pour tous les NodeIds définis dans le présent document est défini à l'Annexe A.

Enotna arhitektura OPC - 24. del: Časovni razporejevalnik (IEC 62541-24:2026)

IEC 62541-24:2026 določa informacijski model OPC UA za izpostavitev informacij o datumih in časih, ko OPC UA strežnik izvede določena dejanja. Te urnike je mogoče po želji tudi spreminjati prek informacijskega modela.
Urnik določa, na katere datume so dejanja aktivna, in lahko vključuje sklicevanje na globalne koledarje, ki predstavljajo določene datume, na primer državne praznike. Poleg tega urnik določa čase in dejanja, ki bodo izvedena ob teh časih. Model določa pisanje spremenljivk (Variables) in klicanje metod (Methods), vendar ga je mogoče razširiti tudi na druga dejanja.
NamespaceUri za vse NodeId-je, določene v tem dokumentu, je opredeljen v Prilogi A.

General Information

• Status: Published
• Public Enquiry End Date: 30-Mar-2024
• Publication Date: 12-Apr-2026
• ICS: 25.040 - Industrial automation systems
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.240.50 - IT applications in industry
• Technical Committee: MOV - Measuring equipment for electromagnetic quantities
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 24-Feb-2026
• Due Date: 01-May-2026
• Completion Date: 13-Apr-2026
• Ref Project: EN IEC 62541-24:2026 - OPC unified architecture - Part 24: Scheduler

Relations

• Refers: SIST EN IEC 62541-6:2026 - OPC unified architecture - Part 6: Mappings (IEC 62541-6:2025)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-4:2020 - OPC Unified Architecture - Part 4: Services (IEC 62541-4:2020)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-4:2026 - OPC unified architecture - Part 4: Services (IEC 62541-4:2025)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-7:2020 - OPC unified architecture - Part 7: Profiles (IEC 62541-7:2020)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-6:2020 - OPC Unified Architecture - Part 6: Mappings (IEC 62541-6:2020)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-3:2026 - OPC unified architecture - Part 3: Address space model (IEC 62541-3:2025)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-7:2026 - OPC Unified Architecture - Part 7: Profiles (IEC 62541-7:2025)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-1:2026 - OPC unified architecture - Part 1: Overview and concepts (IEC 62541-1:2025)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-5:2020 - OPC Unified Architecture - Part 5: Information Model
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-5:2026 - OPC unified architecture - Part 5: Information model (IEC 62541-5:2026)
• Effective Date: 03-Feb-2026
• Refers: SIST EN IEC 62541-3:2020 - OPC unified architecture - Part 3: Address Space Model (IEC 62541-3:2020)
• Effective Date: 03-Feb-2026
• Referred By: SIST EN IEC 62769-7:2021 - Field Device Integration (FDI) - Part 7: Communication devices (IEC 62769-7:2021)
• Effective Date: 20-Feb-2026
• Referred By: SIST EN 62769-3:2015 - Devices and integration in enterprise systems; Field Device Integration - Part 3: FDI Server (IEC 62769-3:2015)
• Effective Date: 20-Feb-2026
• Referred By: SIST EN IEC 62769-1:2023 - Field Device Integration (FDI®) - Part 1: Overview (IEC 62769-1:2023)
• Effective Date: 20-Feb-2026
• Referred By: SIST EN IEC 62769-6:2021 - Field Device Integration (FDI) - Part 6: Technology Mapping (IEC 62769-6:2021
• Effective Date: 20-Feb-2026

Overview

The IEC oSIST prEN IEC 62541-24:2024 standard, titled "OPC Unified Architecture - Part 24: Scheduler," is a vital technical specification developed by the International Electrotechnical Commission (IEC). This document is part of the OPC Unified Architecture (OPC UA) series and introduces a standardized scheduler mechanism designed to enhance automation, control, and enterprise integration processes in industrial and IT environments.

As part of IEC Technical Committee 65 (Industrial-process measurement, control and automation), Subcommittee 65E focuses on devices and integration in enterprise systems. The Scheduler standard outlines a comprehensive information model, object types, and data structures enabling precise scheduling and execution of automated actions in OPC UA-compliant systems.

Key Topics

This standard addresses essential topics including:

• Scheduler Information Model: Provides a detailed architecture to define time-based actions and schedules within OPC UA systems, supporting varied temporal automation needs.
• Use Cases:
  • Scheduling recurring actions on specific weekdays.
  • Scheduling actions on special or one-off dates and intervals.
  • Defining exception schedules and handling global calendar events.
• OPC UA ObjectTypes:
  • CalendarType: Defines calendar structures and methods to manage date lists.
  • ScheduleType: Describes scheduling objects, allowing addition and removal of exceptions dynamically.
• DataTypes:
  • Specialized types such as SpecialEventType, DateType, DateRangeType, TimeType, and BaseActionType format calendar entries, time intervals, and executable actions.
• Profiles and Conformance Units: Framework for standardized compliance ensuring interoperability across vendor implementations.
• Namespaces and Metadata: Defines the organizational structure and identification for scheduler-related components promoting uniform integration.

Applications

The OPC UA Scheduler standard is highly applicable across various industrial and IT applications where time-based automation is required:

• Industrial Automation: Automate control loops, machinery start/stop sequences, and maintenance tasks aligned with factory schedules.
• Process Control Systems: Manage timed process adjustments or safety shutdowns according to predefined plans.
• Building and Energy Management: Schedule HVAC, lighting systems, and energy consumption for optimized performance.
• Enterprise IT Solutions: Coordinate batch jobs, data backups, system updates, and other time-dependent software functions.
• Smart Grids and Utilities: Schedule load balancing and demand response actions for efficient energy distribution.

By enabling consistent scheduling capabilities within OPC UA architecture, this standard facilitates improved operational efficiency, reduces manual intervention, and supports proactive maintenance cycles.

Related Standards

oSIST prEN IEC 62541-24:2024 complements the OPC UA family of standards by enhancing the functional scope with scheduling capabilities:

• IEC 62541 Series: The whole OPC Unified Architecture suite detailing communication protocols, information models, and services for industrial interoperability.
• IEC 62541-99: Common services and core functionalities relevant for scheduler integration.
• IEC 61131: Programming standards for industrial controllers which can utilize OPC UA scheduling for runtime management.
• ISO/IEC Directives, Part 2: Governing the drafting and structure of international standards to ensure uniformity and clarity.

Conclusion

The OPC UA Scheduler standard (oSIST prEN IEC 62541-24:2024) plays a crucial role in modern industrial and IT ecosystems by providing a rigorous and scalable framework for automating time-based actions within OPC UA environments. Its detailed information model, object definitions, and data types enable flexible, reliable scheduling - integral for high-performance industrial process measurement, control, and enterprise integration solutions. Stakeholders in automation, control engineering, and IT management sectors will find this standard invaluable for advancing automation capabilities while ensuring interoperability and compliance.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2026
Enotna arhitektura OPC - 24. del: Časovni razporejevalnik (IEC 62541-24:2026)
OPC unified architecture - Part 24: Scheduler (IEC 62541-24:2026)
OPC Unified Architecture – Teil 24: Scheduler (IEC 62541-24:2026)
Architecture unifiée OPC - Partie 24: Ordonnanceur (IEC 62541-24:2026)
Ta slovenski standard je istoveten z: EN IEC 62541-24:2026
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 62541-24

NORME EUROPÉENNE
EUROPÄISCHE NORM February 2026
ICS 25.040
English Version
OPC unified architecture - Part 24: Scheduler
(IEC 62541-24:2026)
Architecture unifiée OPC - Partie 24: Ordonnanceur OPC Unified Architecture - Teil 24: Scheduler
(IEC 62541-24:2026) (IEC 62541-24:2026)
This European Standard was approved by CENELEC on 2026-02-12. 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,
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 62541-24:2026 E

European foreword
The text of document 65E/1049/CDV, future edition 1 of IEC 62541-24, 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
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.
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 62541-24:2026 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.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 62541-1 - OPC Unified Architecture - Part 1: EN IEC 62541-1 -
Overview and concepts
IEC 62541-3 - 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: IEC 62541-5 -
Information Model
IEC 62541-6 - OPC unified architecture - Part 6: EN IEC 62541-6 -
Mappings
IEC 62541-7 - OPC Unified Architecture - Part 7: Profiles EN IEC 62541-7 -

IEC 62541-24 ®
Edition 1.0 2026-01
INTERNATIONAL
STANDARD
OPC unified architecture -
Part 24: Scheduler
ICS 25.040  ISBN 978-2-8327-0875-0

IEC 62541-24:2026-01(en)
IEC 62541-24:2026 © IEC 2026
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms. 6
4 General information to Scheduler . 7
5 Use cases . 7
5.1 UC01: Scheduling actions on specific times on each weekday . 7
5.2 UC02: Scheduling actions on special dates . 7
5.2.1 Overview . 7
5.2.2 UC002.1: Schedule actions at a specific date. 8
5.2.3 UC002.2: Schedule actions at an interval from a specific date to a
specific date . 8
5.2.4 UC002.3 Schedule actions at a recurring interval . 9
5.2.5 UC002.4 Schedule actions at specific dates defined globally . 9
6 Scheduler Information Model overview . 9
6.1 Overview . 9
6.2 Scheduling Times and Priorities . 10
6.3 Start-up of Schedules. 10
7 OPC UA ObjectTypes . 10
7.1 CalendarType. 10
7.1.1 Overview . 10
7.1.2 ObjectType definition. 11
7.1.3 Method AddDateListElements. 11
7.1.4 Method RemoveDateListElements . 12
7.2 ScheduleType definition . 13
7.2.1 Overview . 13
7.2.2 ObjectType definition. 13
7.2.3 Method AddExceptionScheduleElements . 15
7.2.4 Method RemoveExceptionScheduleElements . 15
8 OPC UA DataTypes . 16
8.1 SpecialEventType . 16
8.2 SpecialEventPeriodType . 17
8.3 CalendarEntryType . 17
8.4 DateType . 18
8.5 Month . 19
8.6 DayOfMonth . 20
8.7 DayOfWeek. 21
8.8 DateRangeType . 22
8.9 TimeActionsType . 23
8.10 BaseActionType . 23
8.11 WriteLocalVariableActionType . 24
8.12 CallLocalMethodActionType . 25
8.13 TimeType . 26
8.14 DailyScheduleType . 26
IEC 62541-24:2026 © IEC 2026
9 Profiles and Conformance Units . 27
10 Namespaces . 27
10.1 Namespace Metadata . 27
10.2 Handling of OPC UA Namespaces . 28
Annex A (normative)  Scheduler Namespace and Identifiers . 30
A.1 Namespace and Identifiers for the Scheduler Information Model . 30
A.2 Capability Identifier . 30

Figure 1 – Overview Scheduler Information Model . 9

Table 1 – Example Weekly Schedule . 7
Table 2 – Example Exception Schedule . 8
Table 3 – Example Calendars . 8
Table 4 – CalendarType Definition . 11
Table 5 – CalendarType Attribute values for child Nodes . 11
Table 6 – AddDateListElements Method Arguments . 12
Table 7 – AddDateListElements Method AddressSpace definition . 12
Table 8 – RemoveDateListElements Method Arguments . 12
Table 9 – RemoveDateListElements Method AddressSpace definition . 13
Table 10 – ScheduleType definition . 13
Table 11 – ScheduleType Attribute values for child Nodes . 14
Table 12 – AddExceptionScheduleElements Method Arguments . 15
Table 13 – AddExceptionScheduleElements Method AddressSpace definition . 15
Table 14 – RemoveExceptionScheduleElements Method Arguments . 16
Table 15 – RemoveExceptionScheduleElements Method AddressSpace definition . 16
Table 16 – SpecialEventType Structure . 16
Table 17 – SpecialEventType Definition . 17
Table 18 – SpecialEventPeriodType Union . 17
Table 19 – SpecialEventPeriodType definition . 17
Table 20 – CalendarEntryType Union . 18
Table 21 – CalendarEntryType Definition . 18
Table 22 – DateType Structure . 18
Table 23 – DateType Definition . 19
Table 24 – Month Values . 19
Table 25 – Month Definition . 20
Table 26 – DayOfMonth Values . 20
Table 27 – DayOfMonth Definition . 21
Table 28 – DayOfWeek Values . 21
Table 29 – DayOfWeek Definition . 22
Table 30 – DateRangeType Structure . 22
Table 31 – DateRangeType Definition. 23
Table 32 – TimeActionsType Structure . 23
Table 33 – TimeActionsType Definition . 23
Table 34 – BaseActionType Structure . 24
IEC 62541-24:2026 © IEC 2026
Table 35 – BaseActionType Definition . 24
Table 36 – WriteLocalVariableActionType Structure . 24
Table 37 – WriteLocalVariableActionType Definition. 25
Table 38 – CallLocalMethodActionType Structure . 25
Table 39 – CallLocalMethodActionType Definition . 25
Table 40 – TimeType Structure . 26
Table 41 – TimeType Definition. 26
Table 42 – DailyScheduleType Structure. 26
Table 43 – DailyScheduleType Definition . 27
Table 44 – Profile URIs for Scheduler . 27
Table 45 – NamespaceMetadata Object for this document . 28
Table 46 – Namespaces used in a Scheduler Server . 28
Table 47 – Namespaces used in this document . 29

IEC 62541-24:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPC unified architecture -
Part 24: Scheduler
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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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 62541-24 has been prepared by subcommittee 65E: Devices and integration in enterprise
systems, of IEC technical committee 65: Industrial-process measurement, control and
automation. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
65E/1049/CDV 65E/1106/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
IEC 62541-24:2026 © IEC 2026
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
Throughout this document and the other Parts of the series, certain document conventions are
used:
Italics are used to denote a defined term or definition that appears in the "Terms and definitions"
clause in one of the parts of the 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 also often 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 in 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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 62541-24:2026 © IEC 2026
1 Scope
This part of IEC 62541 specifies an OPC UA information model to expose information, at what
dates and times specific actions are executed by the OPC UA Server. Those schedules can
optionally also be manipulated via the information model.
The schedule defines on which dates they are active, and can also reference global calendars
representing specific dates, for example public holidays. In addition, the schedule defines times
and actions that will be executed at that time. The model defines writing Variables and calling
Methods but can be extended to other actions as well.
The NamespaceUri for all NodeIds defined in this document is defined in Annex A.
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 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
IEC 62541-6, OPC Unified Architecture - Part 6: Mappings
IEC 62541-7, OPC Unified Architecture - Part 7: Profiles
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62541-1,
IEC 62541-3, IEC 62541-4, IEC 62541-5, IEC 62541-7 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
NOTE It is assumed that basic concepts of OPC UA information modelling are understood in this document. This
document will use these concepts to describe the Scheduler Information Model.
3.2 Abbreviated terms
HTTP Hypertext Transfer Protocol
PMS Production Management System
URI Uniform Resource Identifier
XML Extensible Markup Language
IEC 62541-24:2026 © IEC 2026
4 General information to Scheduler
Schedulers allow to define per day of the week specific times at which specific actions are
executed in the OPC UA Server.
In addition, schedulers can define special dates and times at which specific actions are
executed in the OPC UA Server. If such a date occurs, the actions of the special date are
executed, and the weekly schedule is ignored.
A scheduler can define the special dates by either
– defining a concrete date (e.g., 2022-01-17),
– defining a range of dates (e.g., 2022-01-17 until 2022-04-13)
st
– defining repeating dates with wildcards (e.g., every 1 January)
– or referencing global calendars containing for example all public holidays of a year
Per date an array of times and corresponding actions including parameterization is defined,
when the action is executed. Actions can be the writing of Variables or calling Methods but can
also be extended to other actions.
5 Use cases
5.1 UC01: Scheduling actions on specific times on each weekday
The user wants to schedule that at specific times on each individual weekday a specific action
is executed, for example the heating is set to a specific setpoint. In Table 1, an example of such
a schedule is given. It contains the schedule for the heating of a school building, that is not
used over the weekend. For example, it can be used to disable the schedule, e.g. when it is
warm outside during summer.
Table 1 – Example Weekly Schedule
Monday Tuesday Wednesday Thursday Friday Saturday Sunday
00:00 07:00 07:00 07:00 07:00 00:00 00:00
Night On On On On Off Off
07:00 16:30 16:30 16:30 16:30
On Night Night Night Off
16:30
Night
5.2 UC02: Scheduling actions on special dates
5.2.1 Overview
The user wants to schedule that on special dates or date periods a specific action is executed,
for example switching off the heating during public holidays. The user wants to be able to define
those dates individual or reference predefined dates that can be used in several schedules. In
Table 2, an example is given.
IEC 62541-24:2026 © IEC 2026
Table 2 – Example Exception Schedule
Date
Time Value Priority
Day Interval Recurring Reference
Every 05:00 On 11
Saturday of (School
12:00 Off
March 2022 board)
05:00 On
2022-04-03 – 12
2022-04-07 (IT user)
16:30 Off
05:00 On 13
2022-04-01  (facility
manager)
CAL1
Variable 00:00 Off 14
Holidays
CAL2
00:00 Off 15
Set Holidays
CAL3
School 00:00 Off 16
Vacation
The calendars referenced in Table 2 are defined in Table 3.
Table 3 – Example Calendars
Day Interval Recurring Note
CAL1: Variable Holidays
2022-04-18  Easter Monday
2022-05-26  Ascension Day
CAL2: Set Holidays
Jan 01. New Year's
Jan 06. Epiphany
Dec 24. Christmas Eve
Dec 25. Christmas Day
Dec 26. Christmas Day
CAL3: School Vacation
2022-02-21 – 2022-02-25
2022-07-25 – 2022-09-02
2022-12-23 – 2023-01-02
The example shows more detailed use cases, summarized in the following subsections.
5.2.2 UC002.1: Schedule actions at a specific date
As shown in Table 2 in the third entry, a special schedule on a specific date (2022-04-01) shall
be applied.
5.2.3 UC002.2: Schedule actions at an interval from a specific date to a specific date
As shown in Table 2 in the second entry, a special schedule on a specific interval
(2022-04-03 – 2022-04-07) shall be applied.
IEC 62541-24:2026 © IEC 2026
5.2.4 UC002.3 Schedule actions at a recurring interval
As shown in Table 2 in the first entry, a special schedule on a recurring interval (every Saturday
per of March 2022) shall be applied.
5.2.5 UC002.4 Schedule actions at specific dates defined globally
As shown in Table 2 in the last three entries, a special schedule shall be applied on dates
defined globally. The global definition shall support concrete dates (CAL1), recurring dates
(CAL2) and concrete ranges (CAL3).
6 Scheduler Information Model overview
6.1 Overview
This document defines two main ObjectTypes:
– an instance of CalendarType represent a globally defined set of dates that can be referenced
by schedule Objects;
– an instance of ScheduleType represent a schedule, that defines for specific dates or
weekdays specific times and actions, that shall be executed at those times.
An overview is given in Figure 1. Instances of ScheduleType can have a WeeklySchedule,
defining per weekday specific times and per specific time a list of actions that shall be executed
at that time. Optionally, the WeeklySchedule can be configured by OPC UA Clients.
In addition, or as alternative, a schedule Object can have a ExceptionSchedule. This defines
special dates (days), either by defining a concrete date, a range of dates, or recurring dates, or
by referencing instances of CalendarType. The optional Methods
AddExceptionScheduleElements and RemoveExceptionScheduleElements can be used to
configure the ExceptionSchedule by an OPC UA Client.

Figure 1 – Overview Scheduler Information Model
The CalendarType defines a DateList with specific dates. The optional AddDateListElements
and RemoveDateListElements Methods can be used to manipulate the DateList Property by
OPC UA Clients.
IEC 62541-24:2026 © IEC 2026
This document does not define any specific entry points where to find schedule or calendar
Objects. It is expected that they are placed reasonable in the AddressSpace, for example as
child Object of an Object that is manipulated by actions of the schedule Object.
This document does not define any specific mechanism how new schedule or calendar Objects
are added or removed via OPC UA. Information Models using those Objects might define
specific mechanisms like Methods or using the NodeManagement Service Set.
6.2 Scheduling Times and Priorities
A schedule Object can contain a WeeklySchedule with one entry per weekday and / or an
ExceptionSchedule. One of both shall be defined. The WeeklySchedule contains for each day
actions, that should be taken at specific times. The ExceptionSchedule contains specific dates
or ranges of dates, and the corresponding actions that should be taken at specific times. For
example, the ExceptionSchedule can contain an entry with all public holidays and another with
plant holidays. Since the different entries of the ExceptionSchedule might overlap, each entry
contains a priority. If overlapping entries exist, the one with the highest priority is used. If both,
WeeklySchedule and ExceptionSchedule exist, the exception schedule has priority over the
WeeklySchedule. That is, if the exception schedule has a matching date, the exception
schedule is used, otherwise the weekly schedule.
6.3 Start-up of Schedules
When a Server restarts or starts the first time, and when a schedule Object becomes active (by
reaching its EffectivePeriod, see 7.2.2) there are two options how a schedule Object shall react.
If the ApplyLastAfterStart Property is set to TRUE, the Server shall find the last set of actions
that will be executed before the current time and execute those actions. The mechanism to find
the last set of actions is to find the last element in the list of TimeActionsType that occurs on
or before the current time, and then use that element's actions. If no such element is found,
then no action is executed.
If the ApplyLastAfterStart Property is set to FALSE, the Server does not consider any previous
actions and starts executing actions according to the defined schedule defined in the future.
7 OPC UA ObjectTypes
7.1 CalendarType
7.1.1 Overview
The CalendarType provides a list of calendar dates. Each entry in the list describes a specific
date or date pattern, or range of dates. The CalendarType ObjectType is formally defined in
Table 4.
IEC 62541-24:2026 © IEC 2026
7.1.2 ObjectType definition
Table 4 – CalendarType Definition
Attribute Value
BrowseName CalendarType
IsAbstract False
Description Provides a list of calendar dates. Each entry in the list describes a specific date or date
pattern, or range of dates
References NodeClass BrowseName DataType TypeDefinition Other
Subtype of the 0:BaseObjectType
0:HasComponent Variable PresentValue 0:Boolean 0:BaseDataVariableTy M
pe
0:HasProperty Variable DateList CalendarEntryTyp 0:PropertyType M
e[]
0:HasComponent Method AddDateListElements O

0:HasComponent Method RemoveDateListElements O
Conformance Units
Scheduler Calendar Base
This PresentValue indicates the current value of the calendar: True if the current date is in the
DateList and False if it is not. For the current date that local time of the OPC UA Server shall
be considered.
The DateList is an array of elements of which each is either a specific date or date pattern, or
range of dates.
The child Nodes of the CalendarType have additional Attribute values defined in Table 5.
Table 5 – CalendarType Attribute values for child Nodes
BrowsePath Description Attribute
PresentValue Indicates if the current date is in the DateList (true) or not (false)
DateList Array of elements each defining either a specific date or date pattern, or range of
dates
AddDateListElements Adds elements to the DateList
RemoveDateListElements Removes elements of the DateList

7.1.3 Method AddDateListElements
This Method adds entries to the DateList Property. Even if one entry cannot be added, the other
entries are still processed and added, if possible. The signature of this Method is specified
below. Table 6 and Table 7 specify the Arguments and AddressSpace representation,
respectively.
Signature
AddDateListElements (
[in] CalendarEntryType[] CalendarEntries
[out] 0:Int32[]  EntryResults
);
IEC 62541-24:2026 © IEC 2026
Table 6 – AddDateListElements Method Arguments
Argument Description
CalendarEntries An array of calendar entries that shall be added to the DateList Property.
EntryResults An array of results, one entry per entry in CalendarEntries, indicating if the individual entry
could be added. Each result <> 0 indicates, that adding this calendar entry was not
successful.
0 – OK
-1 – Duplicate – Entry already in DateList
-2 – Invalid Format – The entry contains an invalid format, e.g. an invalid range
Values larger 0 can be used for vendor-specific errors.

7.1.3.1 Method Result Codes (defined in Call Service)
Result Code Description
BadNodeIdUnknown IEC 62541-4 defines this code.
BadNotWritable IEC 62541-4 defines this code.
BadOutOfMemory IEC 62541-4 defines this code.

Table 7 – AddDateListElements Method AddressSpace definition
Value
Attribute
AddDateListElements
BrowseName
NodeClass BrowseName DataType TypeDefinition ModellingRule
References
Variable 0:InputArguments 0:Argument[] 0:PropertyType 0:Mandatory
0:HasProperty
Variable 0:OutputArguments 0:Argument[] 0:PropertyType 0:Mandatory
0:HasProperty
7.1.4 Method RemoveDateListElements
This Method removes entries from the DateList Property. Even if one entry cannot be removed,
the other entries are still processed and removed, if possible. The signature of this Method is
specified below. Table 8 and Table 9 specify the Arguments and AddressSpace representation,
respectively.
Signature
RemoveDateListElements (
[in] CalendarEntryType[] CalendarEntries
[out] 0:Int32[]  EntryResults
);
Table 8 – RemoveDateListElements Method Arguments
Argument Description
CalendarEntries An array of calendar entries that shall be removed from the DateList Property.
EntryResults An array of results, one entry per entry in CalendarEntries, indicating if the individual
entry could be removed. Each result <> 0 indicates, that removing this calendar entry
was not successful.
0 – OK
-1 – Not found – Entry is not in DateList
Values larger 0 can be used for vendor-specific errors.

IEC 62541-24:2026 © IEC 2026
Method Result Codes (defined in Call Service)
Result Code Description
BadNodeIdUnknown See IEC 62541-4 for a general description.
BadNotWritable See IEC 62541-4 for a general description.

Table 9 – RemoveDateListElements Method AddressSpace definition
Attribute Value
BrowseName RemoveDateListElements
References NodeClass BrowseName DataType TypeDefinition ModellingRule
0:HasProperty Variable 0:InputArguments 0:Argument[] 0:PropertyType 0:Mandatory
0:HasProperty Variable 0:OutputArguments 0:Argument[] 0:PropertyType 0:Mandatory

7.2 ScheduleType definition
7.2.1 Overview
The ScheduleType defines a periodic schedule that can recur over a range of dates. The
schedule can have optional exceptions at arbitrary times or dates. The basic unit of a schedule
is days, which are divided into two types: normal days within a week and exception days. A
priority mechanism defines which scheduled event is currently valid. The ScheduleType is
formally defined in Table 10.
7.2.2 ObjectType definition
Table 10 – ScheduleType definition
Value
Attribute
ScheduleType
BrowseName
False
IsAbstract
Defines a periodic schedule that can recur over a range of dates. The schedule can have
Description
optional exceptions at arbitrary times or dates. The basic unit of a schedule is days, which are
divided into two types: normal days within a week and exception days. A priority mechanism
defines which scheduled event is currently valid. The schedule includes a PresentValue
Variable whose value describes the current state of the schedule, including a default value
when no schedules are in effect.
Node BrowseName DataType TypeDefinition Other
References
Class
Subtype of the 0:BaseObjectType
Variable ExceptionSchedule SpecialEventType[] 0:PropertyType
0:HasProperty O
Method AddExceptionScheduleEle

0:HasComponent O
ments
Method RemoveExceptionSchedule
0:HasComponent O
Elements
Variable WeeklySchedule DailyScheduleType[7] 0:PropertyType
0:HasProperty O
Variable 0:LocalTime 0:TimeZoneDataType 0:PropertyType
0:HasProperty M
Variable EffectivePeriod DateRangeType 0:PropertyType
0:HasProperty O
Variable ApplyLastAfterStart 0:Boolean 0:PropertyType
0:HasProperty M
Conformance Units
Scheduler Scheduling Base
IEC 62541-24:2026 © IEC 2026
The ExceptionSchedule provides an array of SpecialEventType. If present, each of those
special events describes a sequence of schedule actions that take precedence over a normal
day's behaviour on a special day or days.
The WeeklySchedule provides an array of seven DailyScheduleType. Each entry represents
one day of the week. The first entry in the array represents Monday, the last Sunday. Each
element describes a sequence of times and a list of actions that provides a sequence of
schedule actions on one day of the week when no ExceptionSchedule is in effect.
At least one of the two Properties ExceptionSchedule and WeeklySchedule shall be present.
To manipulate the ExceptionSchedule, the Methods AddExceptionScheduleElements and
RemoveExceptionScheduleElements should be used. This simplifies adding and removing
entries of the array. As the WeeklySchedule is a fixed-size array with a length of 7, there are
no corresponding Methods. Instead, an individual entry of the array can be written by the Client
to change only the schedule of one weekday.
The 0:LocalTime provides information about the local time of the schedule Object. All scheduled
times are UTC time. Clients shall consider this Property to calculate the local time of the
schedule. If this Property is changed, it is server-specific whether the times of the schedule are
adjusted or not. If the Server and the Object the schedule is defined for are in the same local
time, the Object can reference the 0:LocalTime Property of the 0:Server Object.
The EffectivePeriod specifies the range of dates within which the schedule Object is active.
Upon entering its effective period, the object shall execute the defined actions at the defined
times, otherwise it shall not execute any actions.
The ApplyLastAfterStart Property defines if the last set of actions shall be applied when starting
the schedule Object (see 6.3 for details).
The child Nodes of the ScheduleType have additional Attribute values defined in Table 11.
Table 11 – ScheduleType Attribute values for child Nodes
BrowsePath Description Attribute
ExceptionSchedule An array of special events. If present, each of those special events
describes a sequence of schedule actions that take precedence over a
normal day's behaviour on a special day or days.
AddExceptionScheduleElements Adds elements to the ExceptionSchedule
RemoveExceptionScheduleElements Removes elements from the ExceptionSchedule
WeeklySchedule Each entry represents one day of the week. The first entry in the array
represents Monday, the last Sunday. Each element describes a
sequence of times and a list of actions that provides a sequence of
schedule actions on one day of the week when no ExceptionSchedule is
in effect.
0:LocalTime Provides information about the local time of the schedule Object. All
scheduled times are UTC time. Clients shall consider this Property to
calculate the local time of the schedule. If this Property is changed, it is
server-specific whether the times of the schedule are adjusted or not.
EffectivePeriod Specifies the range of dates within which the schedule Object is active.
Upon entering its effective period, the object shall execute the defined
actions at the defined times, otherwise it shall not execute any actions.
ApplyLastAfterStart The ApplyLastAfterStart Property defines if the last set of actions shall
be applied when starting the schedule Object

IEC 62541-24:2026 © IEC 2026
7.2.3 Method AddExceptionScheduleElements
This Method adds entries to the ExceptionSchedule Property. Even if one entry cannot be
added, the other entries are still processed and added, if possible. The signature of this Method
is specified below. Table 12 and Table 13 specify the Arguments and AddressSpace
representation, respectively.
Signature
AddExceptionScheduleElements (
[in] SpecialEventType[] SpecialEvents
[out] 0:Int32[]  EntryResults
);
Table 12 – AddExceptionSc
...