Automation systems and integration — Digital twin framework for manufacturing — Part 4: Information exchange

This document identifies technical requirements for information exchange between entities within the reference architecture. The requirements for information exchange in the following networks are within the scope of this document: — user network that connects the user entity and the digital twin entity; — service network that connects sub-entities within the digital twin entity; — access network that connects the device communication entity to the digital twin entity and to the user entity; — proximity network that connects the device communication entity to the observable manufacturing elements.

Systèmes d'automatisation industrielle et intégration — Cadre technique de jumeau numérique dans un contexte de fabrication — Partie 4: Échange d'informations

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Published
Publication Date
11-Oct-2021
Current Stage
6060 - International Standard published
Start Date
12-Oct-2021
Completion Date
12-Oct-2021
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INTERNATIONAL ISO
STANDARD 23247-4
First edition
2021-10
Automation systems and
integration — Digital twin framework
for manufacturing —
Part 4:
Information exchange
Systèmes d'automatisation industrielle et intégration — Cadre
technique de jumeau numérique dans un contexte de fabrication —
Partie 4: Échange d'informations
Reference number
ISO 23247-4:2021(E)
© ISO 2021
---------------------- Page: 1 ----------------------
ISO 23247-4:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23247-4:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Networking view of the digital twin reference models .............................................................................................. 2

4.1 Overview ...................................................................................................................................................................................................... 2

4.2 User network ............................................................................................................................................................................................ 3

4.3 Service network ..................................................................................................................................................................................... 3

4.4 Access network ...................................................................................................................................................................................... 3

4.5 Proximity network .............................................................................................................................................................................. 4

5 Requirements for information exchange in the user network ........................................................................... 4

5.1 Overview ...................................................................................................................................................................................................... 4

5.2 Provisioning .............................................................................................................................................................................................. 4

5.3 On-demand status acquisition .................................................................................................................................................. 4

5.4 Standardized method for information exchange ..................................................................................................... 4

5.5 Verification of exchanged digital models ........................................................................................................................ 5

5.6 Security ......................................................................................................................................................................................................... 5

5.7 Synchronization .................................................................................................................................................................................... 5

5.8 Exchange of digital models .......................................................................................................................................................... 5

6 Requirements for information exchange in the service network ...................................................................5

7 Requirements for information exchange in access network ................................................................................ 5

7.1 Overview ...................................................................................................................................................................................................... 5

7.2 Connectivity .............................................................................................................................................................................................. 6

7.3 Standardized method for communication ..................................................................................................................... 6

7.4 Synchronization .................................................................................................................................................................................... 6

7.5 Transaction method ........................................................................................................................................................................... 6

7.6 Support of mobility ............................................................................................................................................................................. 6

7.7 Security ......................................................................................................................................................................................................... 7

8 Requirements for information exchange in proximity network ...................................................................... 7

8.1 Overview ...................................................................................................................................................................................................... 7

8.2 Support of local connectivity ..................................................................................................................................................... 7

8.3 Support of adaptation ....................................................................................................................................................................... 7

8.4 Support of data volume, transmission efficiency, and storage .................................................................... 7

Annex A (informative) Technical discussion — Implementation options for digital

twin framework for manufacturing ................................................................................................................................................ 8

Annex B (informative) Dynamic scheduling use case ....................................................................................................................13

Annex C (informative) Advanced metrology use case ....................................................................................................................21

Annex D (informative) Optimization of material removal operations use case ................................................29

Annex E (informative) Example of enhanced G-code ......................................................................................................................39

Bibliography .............................................................................................................................................................................................................................41

iii
© ISO 2021 – All rights reserved
---------------------- Page: 3 ----------------------
ISO 23247-4:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 184, Industrial automation systems and

integration, Subcommittee SC 4, Industrial data.
A list of all parts in the ISO 23247 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23247-4:2021(E)
Introduction

The ISO 23247 series defines a framework to support the creation of digital twins of observable

manufacturing elements including personnel, equipment, materials, manufacturing processes, facilities,

environment, products, and supporting documents.

A digital twin assists with detecting anomalies in manufacturing processes to achieve functional

objectives such as real-time control, predictive maintenance, in-process adaptation, Big Data analytics,

and machine learning. A digital twin monitors its observable manufacturing element by constantly

updating relevant operational and environmental data. The visibility into process and execution

enabled by a digital twin enhances manufacturing operation and business cooperation.

The type of manufacturing supported by an implementation of the ISO 23247 framework depends on

the standards and technologies available to model the observable manufacturing elements. Different

manufacturing domains can use different data standards. As a framework, this document does not

prescribe specific data formats and communication protocols.
The scopes of the four parts of this series are defined below:

— ISO 23247-1: General principles and requirements for developing digital twins in manufacturing;

— ISO 23247-2: Reference architecture with functional views;

— ISO 23247-3: List of basic information attributes for the observable manufacturing elements;

— ISO 23247-4: Technical requirements for information exchange between entities within the

reference architecture.
Figure 1 shows how the four parts of the series are related.
© ISO 2021 – All rights reserved
---------------------- Page: 5 ----------------------
ISO 23247-4:2021(E)
Figure 1 — ISO 23247 series structure

Annexes A to E provide use cases that demonstrate the digital twin framework for manufacturing.

The use cases are in the discrete manufacturing domain and the digital twins are modelled using the

ISO 10303 series. In other domains, different standards and technologies can be used. For example,

in oil and gas, the digital twins may be modelled using the ISO 15926 series, and for building and

construction, the digital twins may be modelled using the ISO 16739 series.
© ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 23247-4:2021(E)
Automation systems and integration — Digital twin
framework for manufacturing —
Part 4:
Information exchange
1 Scope

This document identifies technical requirements for information exchange between entities within the

reference architecture.

The requirements for information exchange in the following networks are within the scope of this

document:
— user network that connects the user entity and the digital twin entity;
— service network that connects sub-entities within the digital twin entity;

— access network that connects the device communication entity to the digital twin entity and to the

user entity;

— proximity network that connects the device communication entity to the observable manufacturing

elements.
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.

ISO 23247-1, Automation systems and integration — digital twin framework for manufacturing — Part 1:

Overview and general principles

ISO 23247-2, Automation systems and integration — digital twin framework for manufacturing — Part 2:

Reference architecture
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 23247-1 and the following

apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org
3.1
device communication entity
(set of) system or device providing device communication

EXAMPLE A cell controller sending instructions to the devices in a manufacturing cell, and collecting results

from sensors on the devices.
© ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 23247-4:2021(E)
[SOURCE: ISO 23247-2:2021, 3.4]
3.2
digital twin entity

(set of) system(s) providing functionalities for the digital twins such as realisation, management,

synchronization, and simulation

EXAMPLE A system providing simulation, synchronization, and data analytics for a manufacturing cell.

[SOURCE: ISO 23247-2:2021, 3.6]
3.3
user entity

human users, applications, and systems that use the services provided by the digital twin entity

EXAMPLE An enterprise resource planning (ERP) system that uses the application programming interfaces

(APIs) provided by a digital twin application to update the current status of resources in its database.

[SOURCE: ISO 23247-2:2021, 3.8]
3.4
visualization

use of computer graphics and image processing to present models or

characteristics of processes or objects for supporting human understanding

Note 1 to entry: Example: A visual display of a computerized numerical control (CNC) machine milling an

aluminium block.

[SOURCE: ISO/IEC 2382:2015, modified — Note 1 to entry changed to address manufacturing examples.

Note 2 to entry and Note 3 to entry deleted.]
4 Networking view of the digital twin reference models
4.1 Overview

ISO 23247-2 defines reference models of the digital twin framework for manufacturing, and a functional

view of those reference models. This document defines a networking view. The networking view shall

apply to the reference models given in ISO 23247-2.

Figure 2 shows the four types of communication networks that are used to connect the entities

described in the reference models of ISO 23247-2.
© ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 23247-4:2021(E)
Key
1 user network
2 service network
3 access network
4 proximity network
Figure 2 — Networking view of digital twin reference models
4.2 User network

The user network connects the user entity with the digital twin entity. Through this network, the user

entity makes use of the digital twin instances managed by the digital twin entity.

The user network can be either public Internet or private intranet.
4.3 Service network

The service network connects the operation and management sub-entity, application and service

sub-entity, and resource access and interchange sub-entity. The service network is typically a wired

network running IP-based protocols.

If the digital twin entity is implemented as a single private system, then a service network is not

necessary.
4.4 Access network

The access network connects the device communication entity with the digital twin entity and the user

entity. The data collection sub-entity transmits data collected from the OMEs to the digital twin entity.

The device control sub-entity transmits commands from the user entity or the digital twin entity to

control the OMEs.
© ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 23247-4:2021(E)

The access network can be a wired communication network such as local area network (LAN) or

wireless communication network such as wireless LAN (WLAN) and mobile (cellular) network. The

access network generally adopts IP-based communication protocols regardless of communication type.

4.5 Proximity network

The proximity network connects the device communication entity with the OMEs. Through this

network, the device communication entity transmits commands to OMEs that are industrial devices,

and receives results from OMEs that are industrial sensors.

The proximity network can be an Industrial Ethernet or a proprietary network with a specialized

configuration. Some networks use protocols other than IP. However, if an OME is physically attached or

integrated into the device communication entity then the proximity network is not necessary.

5 Requirements for information exchange in the user network
5.1 Overview

The user network shall enable the exchange of information between the user entity and the digital twin

entity. The information shall be exchanged to enable services and applications such as visualization,

process monitoring, statistical analysis, and simulation. The information is defined in ISO 23247-3.

5.2 Provisioning

The user network shall enable the delivery of information to configure a digital twin to an initial state.

EXAMPLE 1 The digital twin of a product is provisioned at the start of its life from information contained in

Product lifecycle management (PLM). This information can be product requirements, 3D models, configuration,

simulation models, and traceability.

EXAMPLE 2 The digital twin of a work cell is provisioned at the start of its life from information in PLM or

other data sources. This information can be kinematics, capacity, capability, certification, and calibration.

EXAMPLE 3 The digital twin of a process is provisioned at the start of its life from information in PLM or

other data sources. This information can be high-level and low-level process plans, production schedule, and

manufacturing requirements.
5.3 On-demand status acquisition

The user network shall enable the delivery of information on the current state of the OMEs as

represented by its digital twin.

The user network shall enable the delivery of information on the historical state of the OMEs as

represented by its digital twin.

EXAMPLE 1 A user entity queries a digital twin entity, so that it can show the current status of a machine by

creating a visualization of the current geometry of a part.

EXAMPLE 2 A user entity queries a digital twin entity, so that it can dynamically predict the remaining life for

a cutting tool by analysing its previous machining activities.
5.4 Standardized method for information exchange
The user network shall use standardized methods for exchanging information.

NOTE As described in A.2.1, examples for standardized protocol include REST and HTTP.

© ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 23247-4:2021(E)
5.5 Verification of exchanged digital models

The standardized method for information exchange should include methods for verifying the syntax

and semantics of the exchanged model and validating its contents.

NOTE As described in A.2.1, examples of information models with methods for checking syntax and

semantics include STEP and QIF.
5.6 Security
The user network shall maintain security and privacy of the digital twin.
NOTE Standard such as IEC 62443 define a protocol for secure communication.
5.7 Synchronization

The user network shall enable applications to operate on digital models that have been appropriately

synchronized. The rate of synchronization depends on the application.
5.8 Exchange of digital models

The user network shall enable exchange of information about the digital representation of the OMEs.

The communication shall allow applications to operate on common models of the OMEs. Depending

on the application, it is possible that the types of OMEs shown in Figure 3 need to be modelled for

information exchange.
Figure 3 — Type of digital models for exchange

NOTE Several standards define information for one or more of the OME types but no single standard has

been identified for all types of OME at the time of publication.
6 Requirements for information exchange in the service network

The Service network is used to transmit information between sub-entities of the digital twin entity. As

such, this network can be private to a particular implementation of the digital twin entity and does not

need to be defined by this document.
7 Requirements for information exchange in access network
7.1 Overview

The access network connects the device communication entity to other entities. The device

communication entity collects information about the OMEs as they operate using an appropriate

streaming protocol. The device communication entity controls the OMEs by sending commands in a

language understood by the OMEs.
© ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 23247-4:2021(E)
7.2 Connectivity

Depending on the circumstances, a connection to the device communication entity may be discovered

dynamically using an appropriate protocol or using a fixed network address. In either case, the

connection delivers data about the OMEs to the digital twin entity.

EXAMPLE 1 With a fixed network address, an MTConnect agent for a machine tool on the shop floor is

published to the network as URL 192.168.0.1:5000. In this case, the digital twin for the machine tool uses this

address to listen for changes to its OME.

EXAMPLE 2 With a dynamic network address, an MQTT subscriber discovers the availability of a data stream

from the device communication entity responsible for the OMEs and uses the information to update its digital

twin.
7.3 Standardized method for communication

The access network shall provide a standardized method for delivering data collected by the device

communication entity. The method shall include information sufficient to identify the OMEs, and

describe each change that has occurred to a monitored characteristic of the OME.

The access network shall provide a standardized method for delivering data to control the OMEs

through the device communication entity.
7.4 Synchronization

The access network shall enable the digital twin to be connected to its OME. The bandwidth and latency

shall be sufficient to support the required level of synchronization.

NOTE 1 IEC has defined standards that describe various synchronization methods for industrial enterprises.

NOTE 2 The latency requirements for servicing an urgent fault or alarm are different to those for updating a

3D model.
7.5 Transaction method

The access network shall support any of the three types of transaction methods that follow:

— PULL method: requester requests information from the provider;

NOTE 1 The digital twin entity is the requester and the device communication entity is the provider.

— PUSH method: sender sends new or changed information to the receiver;

NOTE 2 The digital twin entity is the receiver and the device communication entity is the sender.

— PUBLISH method: publisher publishes data to be received by the subscribers.

NOTE 3 The digital twin entity is the subscriber and the device communication entity is the publisher.

The PUBLISH method is recommended, when multiple digital twin entities are listening to a single

device communication entity.
7.6 Support of mobility

If the network location of the device communication entity changes, then the access network shall

maintain the connectivity to its digital twin.
© ISO 2021 – All rights reserved
---------------------- Page: 12 ----------------------
ISO 23247-4:2021(E)
7.7 Security
The access network shall maintain security and privacy of the digital twin.
NOTE Standards such as IEC 62443 define protocols for secure communication.
8 Requirements for information exchange in proximity network
8.1 Overview

The proximity network is an interface between the device communication entity and the OMEs. The

proximity network is not necessary if the device communication entity is hosted on the OME.

8.2 Support of local connectivity

The proximity network shall connect the device communication entity to the OMEs using industrial

ethernet or a proprietary network.
8.3 Support of adaptation

The proximity network shall support adaptation of data received from OMEs to data that is understood

by the device communication entity.
8.4 Support of data volume, transmission efficiency, and storage

The proximity network shall support data volume, transmission efficiency, and storage necessary to

transmit information between the device communication entity and OMEs.
© ISO 2021 – All rights reserved
---------------------- Page: 13 ----------------------
ISO 23247-4:2021(E)
Annex A
(informative)
Technical discussion — Implementation options for digital
twin framework for manufacturing
A.1 Acronyms used in Annexes A to E

This clause lists acronyms of protocols or standards that can be considered as an implementation

options of digital twin framework for manufacturing.
3D PDF 3-dimensional portable document format
AAS asset administration shell
AES advanced encryption standard
AMF additive manufacturing file format
API application program interface
ASTM American society for testing and materials
AutomationML automation markup language
B2MML business to manufacturing markup language
CAD computer aided design
CAM computer aided manufacturing
CBC cipher-block chaining
CCM counter with CBC-MAC
CFX connected factory exchange
COLLADA collaborative design activity
EASA European aviation safety agency
ECDHE elliptic-curve diffie–hellman
EtherCAT ethernet for control automation technology
FAA federal aviation administration
FBX filmbox
HTTP hypertext transfer protocol
IoT Internet of Things
IPC inter-process communication
© ISO 2021 – All rights reserved
---------------------- Page: 14 ----------------------
ISO 23247-4:2021(E)
ISA international society of automation
JSON Javascript object notation
JT Jupiter tessellation
LwM2M lightweight machine to machine
MES manufacturing execution system
MOM manufacturing operations management
MQTT message queuing telemetry transport
MTConnect machine tool connect
OCF open connectivity foundation
OPC-UA open platform communications - unified architecture
OpenGL open graphics library
PLC programmable logic controller
PSK phase-shift keying
QIF quality information framework
RAPINet real-time automation protocols for industrial ethernet
RDF resource description framework
REST representational state transfer
RSA Rivest–Shamir–Adleman
SHA secure hash algorithm
STEP STandard for the Exchange of Product model data
STL standard template library
TSN time-sensitive networking
WebGL web graphics library
XML extensible markup language
A.2 Information exchange examples
A.2.1 General

Figure A.1 shows how information may be exchanged within a digital twin framework using currently

available communication protocols.
© ISO 2021 – All rights reserved
---------------------- Page: 15 ----------------------
ISO 23247-4:2021(E)
Key
OME observable manufacturin
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23247-4
ISO/TC 184/SC 4
Automation systems and
Secretariat: ANSI
integration — Digital twin framework
Voting begins on:
2021-06-18 for manufacturing —
Voting terminates on:
Part 4:
2021-08-13
Information exchange
Systèmes d'automatisation industrielle et intégration — Cadre
technique de jumeau numérique dans un contexte de fabrication —
Partie 4: Echange d'informations
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 23247-4:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23247-4:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23247-4:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Networking view of the digital twin reference models ................................................................................................ 2

4.1 Overview ...................................................................................................................................................................................................... 2

4.2 User network ............................................................................................................................................................................................ 3

4.3 Service network ..................................................................................................................................................................................... 3

4.4 Access network ....................................................................................................................................................................................... 3

4.5 Proximity network ............................................................................................................................................................................... 4

5 Requirements for information exchange in the user network ............................................................................. 4

5.1 Overview ...................................................................................................................................................................................................... 4

5.2 Provisioning ............................................................................................................................................................................................... 4

5.3 On-demand status acquisition ................................................................................................................................................... 4

5.4 Standardized method for information exchange ....................................................................................................... 4

5.5 Verification of exchanged digital models .......................................................................................................................... 5

5.6 Security .......................................................................................................................................................................................................... 5

5.7 Synchronization ..................................................................................................................................................................................... 5

5.8 Exchange of digital models ........................................................................................................................................................... 5

6 Requirements for information exchange in the service network ..................................................................... 5

7 Requirements for information exchange in access network .................................................................................. 5

7.1 Overview ...................................................................................................................................................................................................... 5

7.2 Connectivity ............................................................................................................................................................................................... 6

7.3 Standardized method for communication ...................................................................................................................... 6

7.4 Synchronization ..................................................................................................................................................................................... 6

7.5 Transaction method............................................................................................................................................................................ 6

7.6 Support of mobility ............................................................................................................................................................................. 6

7.7 Security .......................................................................................................................................................................................................... 7

8 Requirements for information exchange in proximity network ........................................................................ 7

8.1 Overview ...................................................................................................................................................................................................... 7

8.2 Support of local connectivity ...................................................................................................................................................... 7

8.3 Support of adaptation ....................................................................................................................................................................... 7

8.4 Support of data volume, transmission efficiency, and storage ...................................................................... 7

Annex A (informative) Technical discussion — Implementation options for digital

twin framework for manufacturing .................................................................................................................................................. 8

Annex B (informative) Dynamic scheduling use case ......................................................................................................................13

Annex C (informative) Advanced metrology use case ......................................................................................................................21

Annex D (informative) Optimization of material removal operations use case ...................................................29

Annex E (informative) Example of enhanced G-code ........................................................................................................................39

Bibliography .............................................................................................................................................................................................................................41

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23247-4:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 184, Industrial automation systems and

integration, Subcommittee SC 4 Industrial data.
A list of all parts in the ISO 23247 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23247-4:2021(E)
Introduction

The ISO 23247 series defines a framework to support the creation of digital twins of observable

manufacturing elements including personnel, equipment, materials, manufacturing processes, facilities,

environment, products, and supporting documents.

A digital twin assists with detecting anomalies in manufacturing processes to achieve functional

objectives such as real-time control, predictive maintenance, in-process adaptation, Big Data analytics,

and machine learning. A digital twin monitors its observable manufacturing element by constantly

updating relevant operational and environmental data. The visibility into process and execution

enabled by a digital twin enhances manufacturing operation and business cooperation.

The type of manufacturing supported by an implementation of the ISO 23247 framework depends on

the standards and technologies available to model the observable manufacturing elements. Different

manufacturing domains can use different data standards. As a framework, this document does not

prescribe specific data formats and communication protocols.
The scopes of the four parts of this series are defined below:

— ISO 23247-1: General principles and requirements for developing digital twins in manufacturing;

— ISO 23247-2: Reference architecture with functional views;

— ISO 23247-3: List of basic information attributes for the observable manufacturing elements;

— ISO 23247-4: Technical requirements for information exchange between entities within the

reference architecture.
Figure 1 shows how the four parts of the series are related.
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ISO/FDIS 23247-4:2021(E)
Figure 1 — ISO 23247 series structure

Annexes A to E provide use cases that demonstrate the digital twin framework for manufacturing.

The use cases are in the discrete manufacturing domain and the digital twins are modelled using the

ISO 10303 series. In other domains, different standards and technologies can be used. For example,

in oil and gas, the digital twins may be modelled using the ISO 15926 series, and for building and

construction, the digital twins may be modelled using the ISO 16739 series.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23247-4:2021(E)
Automation systems and integration — Digital twin
framework for manufacturing —
Part 4:
Information exchange
1 Scope

This document identifies technical requirements for information exchange between entities within the

reference architecture.

The requirements for information exchange in the following networks are within the scope of this

document:
— user network that connects the user entity and the digital twin entity;
— service network that connects sub-entities within the digital twin entity;

— access network that connects the device communication entity to the digital twin entity and to the

user entity;

— proximity network that connects the device communication entity to the observable manufacturing

elements.
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.

ISO 23247-1, Automation systems and integration — digital twin framework for manufacturing — Part 1:

Overview and general principles

ISO 23247-2, Automation systems and integration — digital twin framework for manufacturing — Part 2:

Reference architecture
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 23247-1 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
device communication entity
(set of) system or device providing device communication

EXAMPLE A cell controller sending instructions to the devices in a manufacturing cell, and collecting results

from sensors on the devices
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[SOURCE: ISO 23247-2:—, 3.4]
3.2
digital twin entity

(set of) system(s) providing functionalities for the digital twins such as realisation, management,

synchronization, and simulation

EXAMPLE A system providing simulation, synchronization, and data analytics for a manufacturing cell

[SOURCE: ISO 23247-2:—, 3.6]
3.3
user entity

human users, applications, and systems that use the services provided by the digital twin entity

EXAMPLE An enterprise resource planning (ERP) system that uses the application programming interfaces

(APIs) provided by a digital twin application to update the current status of resources in its database

[SOURCE: ISO 23247-2:—, 3.8]
3.4
visualization

use of computer graphics and image processing to present models or

characteristics of processes or objects for supporting human understanding

Note 1 to entry: Example: A visual display of a computerized numerical control (CNC) machine milling an

aluminium block.

[SOURCE: ISO/IEC 2382:2015, modified — Note 1 to entry changed to address manufacturing examples.

Note 2 to entry and Note 3 to entry deleted.]
4 Networking view of the digital twin reference models
4.1 Overview

ISO 23247-2 defines reference models of the digital twin framework for manufacturing, and a functional

view of those reference models. This document defines a networking view. The networking view shall

apply to the reference models given in ISO 23247-2.

Figure 2 shows the four types of communication networks that are used to connect the entities

described in the reference models of ISO 23247-2.
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ISO/FDIS 23247-4:2021(E)
Key
1 user network
2 service network
3 access network
4 proximity network
Figure 2 — Networking view of digital twin reference models
4.2 User network

The user network connects the user entity with the digital twin entity. Through this network, the user

entity makes use of the digital twin instances managed by the digital twin entity.

The user network can be either public Internet or private intranet.
4.3 Service network

The service network connects the operation and management sub-entity, application and service

sub-entity, and resource access and interchange sub-entity. The service network is typically a wired

network running IP-based protocols.

If the digital twin entity is implemented as a single private system, then a service network is not

necessary.
4.4 Access network

The access network connects the device communication entity with the digital twin entity and the user

entity. The data collection sub-entity transmits data collected from the OMEs to the digital twin entity.

The device control sub-entity transmits commands from the user entity or the digital twin entity to

control the OMEs.
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The access network can be a wired communication network such as local area network (LAN) or

wireless communication network such as wireless LAN (WLAN) and mobile (cellular) network. The

access network generally adopts IP-based communication protocols regardless of communication type.

4.5 Proximity network

The proximity network connects the device communication entity with the OMEs. Through this

network, the device communication entity transmits commands to OMEs that are industrial devices,

and receives results from OMEs that are industrial sensors.

The proximity network can be an Industrial Ethernet or a proprietary network with a specialized

configuration. Some networks use protocols other than IP. However, if an OME is physically attached or

integrated into the device communication entity then the proximity network is not necessary.

5 Requirements for information exchange in the user network
5.1 Overview

The user network shall enable the exchange of information between the user entity and the digital twin

entity. The information shall be exchanged to enable services and applications such as visualization,

process monitoring, statistical analysis, and simulation. The information is defined in ISO 23247-3.

5.2 Provisioning

The user network shall enable the delivery of information to configure a digital twin to an initial state.

EXAMPLE 1 The digital twin of a product is provisioned at the start of its life from information contained in

Product lifecycle management (PLM). This information can be product requirements, 3D models, configuration,

simulation models, and traceability.

EXAMPLE 2 The digital twin of a work cell is provisioned at the start of its life from information in PLM or

other data sources. This information can be kinematics, capacity, capability, certification, and calibration

EXAMPLE 3 The digital twin of a process is provisioned at the start of its life from information in PLM or

other data sources. This information can be high-level and low-level process plans, production schedule, and

manufacturing requirements.
5.3 On-demand status acquisition

The user network shall enable the delivery of information on the current state of the OMEs as

represented by its digital twin.

The user network shall enable the delivery of information on the historical state of the OMEs as

represented by its digital twin.

EXAMPLE 1 A user entity queries a digital twin entity, so that it can show the current status of a machine by

creating a visualization of the current geometry of a part.

EXAMPLE 2 A user entity queries a digital twin entity, so that it can dynamically predict the remaining life for

a cutting tool by analysing its previous machining activities.
5.4 Standardized method for information exchange
The user network shall use standardized methods for exchanging information.

NOTE As described in A.2.1, examples for standardized protocol include REST and HTTP.

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5.5 Verification of exchanged digital models

The standardized method for information exchange should include methods for verifying the syntax

and semantics of the exchanged model and validating its contents.

NOTE As described in A.2.1, examples of information models with methods for checking syntax and

semantics include STEP and QIF.
5.6 Security
The user network shall maintain security and privacy of the digital twin.
NOTE Standard such as IEC 62443 define a protocol for secure communication.
5.7 Synchronization

The user network shall enable applications to operate on digital models that have been appropriately

synchronized. The rate of synchronization depends on the application.
5.8 Exchange of digital models

The user network shall enable exchange of information about the digital representation of the OMEs.

The communication shall allow applications to operate on common models of the OMEs. Depending

on the application, it is possible that the types of OMEs shown in Figure 3 need to be modelled for

information exchange.
Figure 3 — Type of digital models for exchange

NOTE Several standards define information for one or more of the OME types but no single standard has

been identified for all types of OME at the time of publication.
6 Requirements for information exchange in the service network

The Service network is used to transmit information between sub-entities of the digital twin entity. As

such, this network can be private to a particular implementation of the digital twin entity and does not

need to be defined by this document.
7 Requirements for information exchange in access network
7.1 Overview

The access network connects the device communication entity to other entities. The device

communication entity collects information about the OMEs as they operate using an appropriate

streaming protocol. The device communication entity controls the OMEs by sending commands in a

language understood by the OMEs.
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7.2 Connectivity

Depending on the circumstances, a connection to the device communication entity may be discovered

dynamically using an appropriate protocol or using a fixed network address. In either case, the

connection delivers data about the OMEs to the digital twin entity.

EXAMPLE 1 With a fixed network address, an MTConnect agent for a machine tool on the shop floor is

published to the network as URL 192.168.0.1:5000. In this case, the digital twin for the machine tool uses this

address to listen for changes to its OME.

EXAMPLE 2 With a dynamic network address, an MQTT subscriber discovers the availability of a data stream

from the device communication entity responsible for the OMEs and uses the information to update its digital

twin.
7.3 Standardized method for communication

The access network shall provide a standardized method for delivering data collected by the device

communication entity. The method shall include information sufficient to identify the OMEs, and

describe each change that has occurred to a monitored characteristic of the OME.

The access network shall provide a standardized method for delivering data to control the OMEs

through the device communication entity.
7.4 Synchronization

The access network shall enable the digital twin to be connected to its OME. The bandwidth and latency

shall be sufficient to support the required level of synchronization.

NOTE 1 IEC has defined standards that describe various synchronization methods for industrial enterprises.

NOTE 2 The latency requirements for servicing an urgent fault or alarm are different to those for updating a

3D model.
7.5 Transaction method

The access network shall support any of the three types of transaction methods that follow:

— PULL method: requester requests information from the provider;

NOTE 1 The digital twin entity is the requester and the device communication entity is the provider.

— PUSH method: sender sends new or changed information to the receiver;

NOTE 2 The digital twin entity is the receiver and the device communication entity is the sender.

— PUBLISH method: publisher publishes data to be received by the subscribers.

NOTE 3 The digital twin entity is the subscriber and the device communication entity is the publisher.

The PUBLISH method is recommended, when multiple digital twin entities are listening to a single

device communication entity.
7.6 Support of mobility

If the network location of the device communication entity changes, then the access network shall

maintain the connectivity to its digital twin.
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7.7 Security
The access network shall maintain security and privacy of the digital twin.
NOTE Standards such as IEC 62443 define protocols for secure communication.
8 Requirements for information exchange in proximity network
8.1 Overview

The proximity network is an interface between the device communication entity and the OMEs. The

proximity network is not necessary if the device communication entity is hosted on the OME.

8.2 Support of local connectivity

The proximity network shall connect the device communication entity to the OMEs using industrial

ethernet or a proprietary network.
8.3 Support of adaptation

The proximity network shall support adaptation of data received from OMEs to data that is understood

by the device communication entity.
8.4 Support of data volume, transmission efficiency, and storage

The proximity network shall support data volume, transmission efficiency, and storage necessary to

transmit information between the device communication entity and OMEs.
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ISO/FDIS 23247-4:2021(E)
Annex A
(informative)
Technical discussion — Implementation options for digital
twin framework for manufacturing
A.1 Acronyms used in Annexes A to E

This clause lists acronyms of protocols or standards that can be considered as an implementation

options of digital twin framework for manufacturing.
3D PDF 3-dimensional portable document format
AAS asset administration shell
AES advanced encryption standard
AMF additive manufacturing file format
API application program interface
ASTM American society for testing and materials
AutomationML automation markup language
B2MML business to manufacturing markup language
CAD computer aided design
CAM computer aided manufacturing
CBC cipher-block chaining
CCM counter with CBC-MAC
CFX connected factory exchange
COLLADA collaborative design activity
EASA European aviation safety agency
ECDHE elliptic-curve diffie–hellman
EtherCAT ethernet for control automation technology
FAA federal aviation administration
FBX filmbox
HTTP hypertext transfer protocol
IoT Internet of Things
IPC inter-process communication
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ISA international society of automation
JSON Javascript object notation
JT Jupiter tessellation
LwM2M lightweight machine to machine
MES manufacturing execution system
MOM manufacturing operations management
MQTT message queuing telemetry transport
MTConnect machine tool connect
OCF open connectivity foundation
OPC-UA open platform communications - unified architecture
OpenGL open graphics library
PLC programmable logic controller
PSK phase-shift key
...

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