EN 61784-3-18:2011

Industrial communication networks - Profiles - Part 3-18: Functional safety fieldbuses - Additional specifications for CPF 18

IEC 61784-3-18:2011 specifies a safety communication layer (services and protocol) based on CPF 18 of IEC 61784-2 and IEC 61158 Type 22. It identifies the principles for functional safety communications defined in IEC 61784-3 that are relevant for this safety communication layer.

Industrielle Kommunikationsnetze - Profile - Teil 3-18: Funktional sichere Übertragung bei Feldbussen - Zusätzliche Festlegungen für die Kommunikationsprofilfamilie 18

Réseaux de communication industriels - Profils - Partie 3-18: Bus de terrain à sécurité fonctionnelle - Spécifications supplémentaires pour le CPF 18

La CEI 61784-3-18:2011 spécifie une couche de communication relative à la sécurité (services et protocole) fondée sur le CPF 18 de la CEI 61784-2 et le type 22 de la CEI 61158. Elle identifie les principes applicables aux communications de sécurité fonctionnelle définies dans la CEI 61784-3, et appropriés à cette couche de communication de sécurité.",PE

Industrijska komunikacijska omrežja - Profili - 3-18. del: Funkcijska varnost procesnih vodil - Dodatne specifikacije za CPF 18 (IEC 61784-3-18:2011)

Ta del serije IEC 61784-3 določa varnostno komunikacijsko plast (storitve in protokol) na osnovi CPF 18 IEC 61784-2 in IEC 61158 tipa 22. Določa načela za funkcijsko varnost komunikacij, opredeljena v IEC 61784-3, ki so pomembna za to varnostno komunikacijsko plast. Ta del opredeljuje mehanizme za prenos sporočil, pomembnih za varnost, med udeleženci v porazdeljenem omrežju z uporabo tehnologije vodil v skladu z zahtevami IEC 61508 serije 2 za funkcijsko varnost. Ti mehanizmi se lahko uporabljajo v različnih industrijskih aplikacijah, kot je procesni nadzor, proizvodna avtomatizacija in stroji. Ta del zagotavlja smernice za razvijalce in ocenjevalce skladnih pripomočkov in sistemov.

General Information

• Status: Published
• Publication Date: 30-Jun-2011
• Withdrawal Date: 24-May-2014
• ICS: 13.110 - Safety of machinery
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.100.05 - Multilayer applications
• Technical Committee: CLC/TC 65X - Industrial-process measurement, control and automation
• Drafting Committee: IEC/SC 65C - IEC_SC_65C
• Parallel Committee: IEC/SC 65C - IEC_SC_65C
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 01-Jul-2011
• Completion Date: 01-Jul-2011
• Ref Project: SIST EN 61784-3-18:2011 - Industrial communication networks - Profiles - Part 3-18: Functionnal safety fieldbuses - Additional specifications for CPF 18 (IEC 61784-3-18:2011)

Relations

• Amended By: EN 61784-3-18:2011/A1:2017 - Industrial communication networks - Profiles - Part 3-18: Functional safety fieldbuses - Additional specifications for CPF 18
• Effective Date: 07-Jun-2022
• Amended By: EN 61784-3-18:2011/A2:2021 - Industrial communication networks - Profiles - Part 3-18: Functional safety fieldbuses - Additional specifications for CPF 18
• Effective Date: 07-Jun-2022
• Amended By: EN 61784-3-2:2017 - Industrial communication networks - Profiles - Part 3-2: Functional safety fieldbuses - Additional specifications for CPF 2
• Effective Date: 30-Jul-2014

Overview

EN 61784-3-18:2011 (identical to IEC 61784-3-18:2011) defines an industrial safety communication layer for functional safety fieldbuses based on CPF 18 (IEC 61784-2) and IEC 61158 Type 22. The standard specifies the services and protocol required to transport safety-relevant data across a Type 22 fieldbus and identifies the principles from IEC 61784-3 that apply to this safety layer. It is intended for use where deterministic, certified communication of safety information is required in industrial process and automation systems.

Key topics and technical requirements

• Safety communication layer architecture: structure and relationships between the safety application layer (FAL), data-link layer (DLL) and physical layer (PhL) within CPF 18.
• Safety communication services: definitions for Safety Process Data Objects (SPDO), Safety Heartbeat (SHB), and Delay Monitoring (SDM).
• Safety protocol elements: Safety PDU formats, embedding safety PDUs in Type 22 PDUs, and protocol procedures for reliable delivery.
• Management and configuration: Safety communication layer management (SALMT), parameter handling and the Safety Object Dictionary that documents safety-related objects and device profiles.
• System-level requirements: installation guidelines, indicators and switches, maintenance and safety manual requirements, calculation of worst‑case safety function response time, and constraints for probabilistic/system characteristic calculations.
• Assessment and conformance: guidance and informative annexes for evaluating CPF 18 safety profiles and their implementation.
• Error detection and mitigation: requirements for detecting communication errors and applying safety measures appropriate for functional safety applications.

Practical applications

• Implementing certified functional safety fieldbus communication for process industries (chemical, oil & gas, power generation).
• Integrating safety-capable devices (sensors, actuators, controllers) on CPF 18 Type 22 networks such as SafetyNET p™ (FSCP 18/1).
• Designing safety instrumented systems (SIS) and safety-related control loops that require deterministic, time-bounded delivery of safety data.
• Creating product documentation, safety manuals and validation artifacts for device manufacturers and system integrators.

Who should use this standard

• Control system architects and automation engineers
• Fieldbus and device manufacturers implementing CPF 18 safety profiles
• Functional safety assessors, certification bodies and compliance teams
• System integrators and process safety managers deploying safety fieldbuses

Related standards (normative and practical)

• IEC 61784-3 (general rules for functional safety fieldbuses)
• IEC 61784-2 (CPF 18 profiles)
• IEC 61158 (Type 22 fieldbus specifications)
• IEC 61508 / IEC 61511 (functional safety lifecycle and system requirements)

Keywords: IEC 61784-3-18, SIST EN 61784-3-18, functional safety fieldbus, CPF 18, safety communication layer, SafetyNET p, SPDO, safety heartbeat, industrial communication networks, IEC 61158 Type 22.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2011
Industrijska komunikacijska omrežja - Profili - 3-18. del: Funkcijska varnost
procesnih vodil - Dodatne specifikacije za CPF 18 (IEC 61784-3-18:2011)
Industrial communication networks - Profiles - Part 3-18: Functionnal safety fieldbuses -
Additional specifications for CPF 18 (IEC 61784-3-18:2011)
Industrielle Kommunikationsnetze - Profile - Teil 3-18: Funktional sichere Übertragung
bei Feldbussen - Zusätzliche Festlegungen für die Kommunikationsprofilfamilie 18 (IEC
61784-3-18:2011)
Réseaux de communication industriels - Profils - Partie 3-18: Bus de terrain à sécurité
fonctionnelle - Spécifications supplémentaires pour le CPF 18 (CEI 61784-3-18:2011)
Ta slovenski standard je istoveten z: EN 61784-3-18:2011
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.100.05 9HþVORMQHXSRUDEQLãNH Multilayer applications
UHãLWYH
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61784-3-18
NORME EUROPÉENNE
July 2011
EUROPÄISCHE NORM
ICS 13.110; 25.040.40; 35.100.05

English version
Industrial communication networks -
Profiles -
Part 3-18: Functional safety fieldbuses -
Additional specifications for CPF 18
(IEC 61784-3-18:2011)
Réseaux de communication industriels -  Industrielle Kommunikationsnetze -
Profils - Profile -
Partie 3-18: Bus de terrain à sécurité Teil 3-18: Funktional sichere Übertragung
fonctionnelle - bei Feldbussen -
Spécifications supplémentaires pour le Zusätzliche Festlegungen für die
CPF 18 Kommunikationsprofilfamilie 18
(CEI 61784-3-18:2011) (IEC 61784-3-18:2011)

This European Standard was approved by CENELEC on 2011-05-25. 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 Central Secretariat 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 Central Secretariat 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, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61784-3-18:2011 E
Foreword
The text of document 65C/639/FDIS, future edition 1 of IEC 61784-3-18, prepared by SC 65C, Industrial
networks, of IEC TC 65, Industrial-process measurement, control and automation, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 61784-3-18 on 2011-05-25.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2012-02-25
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2014-05-25
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61784-3-18:2011 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60204-1 NOTE  Harmonized as EN 60204-1.
1)
IEC 61131-6 NOTE  Harmonized as EN 61131-6 .
IEC 61158 series NOTE  Harmonized in EN 61158 series.
IEC 61326-3-1 NOTE  Harmonized as EN 61326-3-1.
IEC 61326-3-2 NOTE  Harmonized as EN 61326-3-2.
IEC 61496 series NOTE  Harmonized in EN 61496 series.
IEC 61508-1:2010 NOTE  Harmonized as EN 61508-1:2010.
IEC 61508-4:2010 NOTE  Harmonized as EN 61508-4:2010.
IEC 61508-5:2010 NOTE  Harmonized as EN 61508-5:2010.
IEC 61511 series NOTE  Harmonized in EN 61511 series.
IEC 61784-1 NOTE  Harmonized as EN 61784-1.
IEC 61784-5 series NOTE  Harmonized in EN 61784-5 series.
IEC 61800-5-2 NOTE  Harmonized as EN 61800-5-2.
IEC 62061 NOTE  Harmonized as EN 62061.
ISO 10218-1 NOTE  Harmonized as EN ISO 10218-1.
ISO 12100-1 NOTE  Harmonized as EN ISO 12100-1.
ISO 13849-1 NOTE  Harmonized as EN ISO 13849-1.

1)
At draft stage.
- 3 - EN 61784-3-18:2011
ISO 13849-2 NOTE  Harmonized as EN ISO 13849-2.
ISO 14121 NOTE  Harmonized as EN ISO 14121.
__________
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application 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  When an international publication has been modified by common modifications, indicated by
(mod), the relevant EN/HD applies.

Publication Year Title EN/HD Year

IEC 61158-3-22 - Industrial communication networks - Fieldbus - -
specifications -
Part 3-22: Data-link layer service definition -
Type 22 elements
IEC 61158-4-22 - Industrial communication networks - Fieldbus - -
specifications -
Part 4-22: Data-link layer protocol
specification - Type 22 elements

IEC 61158-5-22 - Industrial communication networks - Fieldbus - -
specifications -
Part 5-22: Application layer service definition -
Type 22 elements
IEC 61158-6-22 - Industrial communication networks - Fieldbus - -
specifications -
Part 6-22: Application layer protocol
specification - Type 22 elements

IEC 61508 Series Functional safety of EN 61508 Series
electrical/electronic/programmable electronic
safety-related systems
IEC 61508-2 2010 Functional safety of EN 61508-2 2010
electrical/electronic/programmable electronic
safety-related systems -
Part 2: Requirements for
electrical/electronic/programmable electronic
safety-related systems
IEC 61784-2 2010 Industrial communication networks - EN 61784-2 2010
Profiles -
Part 2: Additional fieldbus profiles for real-time
networks based on ISO/IEC 8802-3

IEC 61784-3 2010 Industrial communication networks - EN 61784-3 2010
Profiles -
Part 3: Functional safety fieldbuses - General
rules and profile definitions
IEC 61918 - Industrial communication networks - EN 61918 -
Installation of communication networks in
industrial premises
ISO/IEC 10731 - Information technology - Open Systems - -
Interconnection - Basic reference model -
Conventions for the definition of OSI services

IEC 61784-3-18 ®
Edition 1.0 2011-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Profiles
Part 3-18: Functional safety fieldbuses – Additional specifications for CPF 18

Réseaux de communication industriels – Profils
Partie 3-18: Bus de terrain de sécurité fonctionnelle – Spécifications
supplémentaires pour le CPF 18

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 13.110, 25.040.40, 35.100.05 ISBN 978-2-88912-475-6

– 2 – 61784-3-18  IEC:2011
CONTENTS
FOREWORD . 5
0 Introduction . 7
0.1 General . 7
0.2 Patent declaration . 9
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, symbols, abbreviated terms and conventions . 11
3.1 Terms and definitions . 11
3.1.1 Common terms and definitions . 11
3.1.2 CPF 18: Additional terms and definitions . 15
3.2 Symbols and abbreviated terms. 16
3.2.1 Common symbols and abbreviated terms . 16
3.2.2 CPF 18: Additional symbols and abbreviated terms . 17
3.3 Conventions . 17
4 Overview of FSCP 18/1 (SafetyNET p™) . 19
4.1 General . 19
4.2 FSCP 18/1 . 19
5 General . 20
5.1 External documents providing specifications for the profile . 20
5.2 Safety functional requirements . 20
5.3 Safety measures . 20
5.4 Safety communication layer structure . 21
5.5 Relationships with FAL (and DLL, PhL) . 22
5.5.1 General . 22
5.5.2 Data Types . 22
6 Safety communication layer services . 22
6.1 General elements . 22
6.1.1 General . 22
6.1.2 Safety object dictionary . 22
6.1.3 Safety process data object (SPDO) . 22
6.1.4 Safety heartbeat (SHB) . 22
6.1.5 Safety delay monitoring (SDM) . 23
6.2 Communication relation . 23
7 Safety communication layer protocol . 24
7.1 Safety PDU format . 24
7.1.1 General . 24
7.1.2 Safety process data objects (SPDO) . 24
7.1.3 Safety heartbeat (SHB) . 26
7.1.4 Safety PDUs embedded in a Type 22 PDU . 28
7.2 Safety communication layer management (SALMT) . 28
7.3 Safety process data communication . 30
7.4 Safety heartbeat . 32
7.5 Delay monitoring . 33
8 Safety communication layer management . 34
8.1 Parameter handling . 34
8.2 Safety object dictionary . 34

61784-3-18  IEC:2011 – 3 –
8.2.1 General . 34
8.2.2 Communication profile section . 35
8.2.3 Standardized device profile section . 51
9 System requirements . 51
9.1 Indicators and switches . 51
9.1.1 Indicator states and flash rates . 51
9.1.2 Indicators . 51
9.1.3 Switches . 52
9.2 Installation guidelines . 52
9.3 Safety function response time . 52
9.3.1 General . 52
9.3.2 Determination of FSCP 18/1 time expectation behavior . 53
9.3.3 Calculation of the worst case safety function response time . 53
9.4 Duration of demands . 53
9.5 Constraints for calculation of system characteristics . 53
9.5.1 Safety related constraints . 53
9.5.2 Probabilistic considerations . 55
9.6 Maintenance . 55
9.7 Safety manual . 55
10 Assessment . 55
Annex A (informative) Additional information for functional safety communication
profiles of CPF 18 . 57
Annex B (informative) Information for assessment of the functional safety
communication profiles of CPF 18 . 58
Bibliography . 59

Table 1 – Object definition . 18
Table 2 – Safety PDU element definition . 18
Table 3 – Communication errors and detection measures . 21
Table 4 – SPDO PDU structure . 25
Table 5 – SHB request PDU structure . 26
Table 6 – SHB response PDU structure . 27
Table 7 – SHB safety communication layer state encoding . 27
Table 8 – SALMT commands . 28
Table 9 – System states of SALMT state machine. 29
Table 10 – State transitions SALMT state machine . 30
Table 11 – System states of RxSPDO state machine . 31
Table 12 – State transitions RxSPDO state machine . 31
Table 13 – Timeouts . 32
Table 14 – Safety object dictionary structure . 34
Table 15 – Objects of communication section . 35
Table 16 – Device type . 36
Table 17 – Safety ID . 37
Table 18 – Safety consumer heartbeat entry . 37
Table 19 – Safety consumer heartbeat . 38

– 4 – 61784-3-18  IEC:2011
Table 20 – Safety producer heartbeat parameter . 39
Table 21 – Safety bus cycle times . 42
Table 22 – SPDO timeout tolerance . 43
Table 23 – Receive SPDO communication parameter . 43
Table 24 – Transmit SPDO communication parameter . 46
Table 25 – Mapping format . 49
Table 26 – Receive SPDO mapping parameter . 49
Table 27 – Transmit SPDO mapping parameter . 50
Table 28 – Indicator states definiton . 51
Table 29 – STATUS indicator states . 51

Figure 1 – Relationships of IEC 61784-3 with other standards (machinery) . 7
Figure 2 – Relationships of IEC 61784-3 with other standards (process) . 8
Figure 3 – FSCP 18/1 system . 19
Figure 4 – FSCP 18/1 software architecture . 21
Figure 5 – SPDO interaction model . 23
Figure 6 – SHB interaction model . 23
Figure 7 – Safety process data object structure . 24
Figure 8 – Safety heartbeat request structure . 26
Figure 9 – Safety heartbeat response structure . 26
Figure 10 – Safety PDU for FSCP 18/1 embedded in a Type 22 CDC data section . 28
Figure 11 – SALMT state machine . 29
Figure 12 – RxSPDO state machine . 31
Figure 13 – Heartbeat procedure . 32
Figure 14 – Delay measurement principle . 33
Figure 15 – Parameter handling . 34
Figure 16 – Safety response time components . 52
Figure 17 – Considered data fields for message size calculation . 54
Figure 18 – Residual error rate . 55

61784-3-18 © IEC:2011 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES
Part 3-18: Functional safety fieldbuses –
Additional specifications for CPF 18

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, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
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with the International Organization for 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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
International Standard IEC 61784-3-18 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial process measurement, control and
automation.
This standard cancels and replaces IEC/PAS 61784-3-18 published in 2009. This first edition
constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
65C/639/FDIS 65C/649/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 6 – 61784-3-18  IEC:2011
A list of all parts of the IEC 61784-3 series, published under the general title Industrial
communication networks – Profiles – Functional safety fieldbuses, can be found on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
61784-3-18  IEC:2011 – 7 –
0 Introduction
0.1 General
The IEC 61158 fieldbus standard together with its companion standards IEC 61784-1 and
IEC 61784-2 defines a set of communication protocols that enable distributed control of
automation applications. Fieldbus technology is now considered well accepted and well
proven. Thus many fieldbus enhancements are emerging, addressing not yet standardized
areas such as real time, safety-related and security-related applications.
This standard explains the relevant principles for functional safety communications with
reference to IEC 61508 series and specifies several safety communication layers (profiles and
corresponding protocols) based on the communication profiles and protocol layers of
IEC 61784-1, IEC 61784-2 and the IEC 61158 series. It does not cover electrical safety and
intrinsic safety aspects.
Figure 1 shows the relationships between this standard and relevant safety and fieldbus
standards in a machinery environment.
Product standards
ISO 12100-1 and ISO 14121
ISO 12100-1 and ISO 14121
Safety of machinery – Principles for
IEC 61496 IEC 61131-6 IEC 61800-5-2 ISO 10218-1
IEC 61496 IEC 61800-5-2 ISO 10218-1 Safety of machinery – Principles for
IEC 61131-6
design and risk assessment
Safety f. e.g. Safety functions Safety requirements
Safety f. e.g. Safety for PLC Safety functions Safety requirements design and risk assessment
Safety for PLC
(under consideration)
light curtains for drives for robots
light curtains (under consideration) for drives for robots
Design of safety-related electrical, electronic and program-
IEC 61784-4 IEC 62443
IEC 61784-4 IEC 62443
mable electronic control systems (SRECS) for machinery
Security Security
Security Security
(profile-specific) (common part)
(profile-specific) (common part)
SIL based PL based
IEC 61784-5 IEC 61918
IEC 61784-5 IEC 61918
Installation guide Installation guide
Installation guide Installation guide Design objective
(profile-specific) (common part)
(profile-specific) (common part)
Applicable standards
ISO 13849-1, -2
ISO 13849-1, -2
IEC 60204-1
IEC 60204-1
Safety-related parts
Safety-related parts
Safety of electrical
Safety of electrical
IEC 61000-1-2
IEC 61000-1-2 of machinery
of machinery
equipment
equipment
Methodology EMC & FS
Methodology EMC & FS (SRPCS)
(SRPCS)
IEC 61326-3-1
IEC 61784-3
IEC 61784-3 IEC 61326-3-1
Non-electrical
Non-electrical
Test EMC & FS
Functional safety
Functional safety Test EMC & FS
communication
communication
Electrical
Electrical
US: NFPA 79
US: NFPA 79
profiles
profiles
(2006)
(2006)
IEC 62061
IEC 62061
Functional safety
Functional safety
IEC 61158 series /
IEC 61158 series /
for machinery
for machinery
IEC 61784-1, -2 IEC 61508 series
IEC 61784-1, -2 IEC 61508 series (SRECS)
(SRECS)
Functional safety (FS)
Fieldbus for use in Functional safety (FS) (including EMC for
Fieldbus for use in
(including EMC for
(basic standard)
(basic standard) industrial environment)
industrial control systems industrial environment)
industrial control systems
Key
(yellow) safety-related standards
(blue) fieldbus-related standards
(dashed yellow) this standard
IEC  768/11
NOTE Subclauses 6.7.6.4 (high complexity) and 6.7.8.1.6 (low complexity) of IEC 62061 specify the relationship
between PL (Category) and SIL.
Figure 1 – Relationships of IEC 61784-3 with other standards (machinery)

– 8 – 61784-3-18  IEC:2011
Figure 2 shows the relationships between this standard and relevant safety and fieldbus
standards in a process environment.
Product standards
IEC 61496 IEC 61800-5-2 ISO 10218-1
IEC 61131-6
IEC 61496 IEC 61131-6 IEC 61800-5-2 ISO 10218-1
Safety f. e.g. Safety functions Safety requirements
Safety for PLC
Safety f. e.g. Safety for PLC Safety functions Safety requirements
light curtains (under consideration) for drives for robots
(under consideration)
light curtains for drives for robots
IEC 61784-4 IEC 62443
IEC 61784-4 IEC 62443
Security Security
Security Security
(profile-specific) (common part)
(profile-specific) (common part)
See safety standards for machinery
(Figure 1)
IEC 61784-5 IEC 61918
IEC 61784-5 IEC 61918
Installation guide Installation guide
Installation guide Installation guide
(profile-specific) (common part)
(profile-specific) (common part)
Valid also in process industries,
whenever applicable
a)
a)
IEC 61326-3-2
IEC 61326-3-2
EMC and
EMC and
functional safety
functional safety
IEC 61784-3
IEC 61784-3
Functional safety
Functional safety
communication
communication
profiles
profiles
US:
US:
ISA-84.00.01
ISA-84.00.01
b)
b)
(3 parts = modified
IEC 61511 series
IEC 61511 series (3 parts = modified
IEC 61511)
Functional safety –
IEC 61158 series / Functional safety – IEC 61511)
IEC 61158 series /
Safety instrumented
Safety instrumented
IEC 61784-1, -2 IEC 61508 series
IEC 61784-1, -2 IEC 61508 series
systems for the
systems for the
Fieldbus for use in Functional safety (FS)
Functional safety (FS)
Fieldbus for use in DE: VDI 2180
process industry sector DE: VDI 2180
process industry sector
(basic standard)
(basic standard)
industrial control systems Part 1-4
industrial control systems
Part 1-4
Key
(yellow) safety-related standards
(blue) fieldbus-related standards
(dashed yellow) this standard
IEC  769/11
a
For specified electromagnetic environments; otherwise IEC 61326-3-1.
b
EN ratified.
Figure 2 – Relationships of IEC 61784-3 with other standards (process)
Safety communication layers which are implemented as parts of safety-related systems
according to IEC 61508 series provide the necessary confidence in the transportation of
messages (information) between two or more participants on a fieldbus in a safety-related
system, or sufficient confidence of safe behaviour in the event of fieldbus errors or failures.
Safety communication layers specified in this standard do this in such a way that a fieldbus
can be used for applications requiring functional safety up to the Safety Integrity Level (SIL)
specified by its corresponding functional safety communication profile.
The resulting SIL claim of a system depends on the implementation of the selected functional
safety communication profile within this system – implementation of a functional safety
communication profile in a standard device is not sufficient to qualify it as a safety device.

61784-3-18  IEC:2011 – 9 –
This standard describes:
– basic principles for implementing the requirements of IEC 61508 series for safety-
related data communications, including possible transmission faults, remedial
measures and considerations affecting data integrity;
– individual description of functional safety profiles for several communication profile
families in IEC 61784-1 and IEC 61784-2;
– safety layer extensions to the communication service and protocols sections of the
IEC 61158 series.
0.2 Patent declaration
The International Electrotechnical Commission (IEC) draws attention to the fact that it is
claimed that compliance with this document may involve the use of a patent concerning the
functional safety communication profiles for family 18 as follows, where the [xx] notation
indicates the holder of the patent right:
DE 10 2008 007 672.4-31 [PI] Verfahren und Vorrichtung zum Übertragen von
Daten in einem Netzwerk
IEC takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured the IEC that he/she is willing to negotiate licences
either free of charge or under reasonable and non-discriminatory terms and conditions with
applicants throughout the world. In this respect, the statement of the holder of this patent
right is registered with IEC. Information may be obtained from:
Information may be obtained from:
[PI] Pilz GmbH & Co. KG
Felix-Wankel-Str. 2
73760 Ostfildern
GERMANY
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights other than those identified above. IEC shall not be held responsible for
identifying any or all such patent rights.
ISO (www.iso.org/patents) and IEC (http://www.iec.ch/tctools/patent_decl.htm) maintain on-
line data bases of patents relevant to their standards. Users are encouraged to consult the
data bases for the most up to date information concerning patents.

– 10 – 61784-3-18  IEC:2011
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES
Part 3-18: Functional safety fieldbuses –
Additional specifications for CPF 18

1 Scope
This part of the IEC 61784-3 series specifies a safety communication layer (services and
protocol) based on CPF 18 of IEC 61784-2 and IEC 61158 Type 22. It identifies the principles
for functional safety communications defined in IEC 61784-3 that are relevant for this safety
communication layer.
NOTE 1 It does not cover electrical safety and intrinsic safety aspects. Electrical safety relates to hazards such
as electrical shock. Intrinsic safety relates to hazards associated with potentially explosive atmospheres.
This part defines mechanisms for the transmission of safety-relevant messages among
participants within a distributed network using fieldbus technology in accordance with the
requirements of IEC 61508 series for functional safety. These mechanisms may be used in
various industrial applications such as process control, manufacturing automation and
machinery.
This part provides guidelines for both developers and assessors of compliant devices and
systems.
NOTE 2 The resulting SIL claim of a system depends on the implementation of the selected functional safety
communication profile within this system – implementation of a functional safety communication profile according to
this part in a standard device is not sufficient to qualify it as a safety device.
2 Normative references
The following referenced documents are indispensable for the application 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 61158-3-22, Industrial communication networks – Fieldbus specifications – Part 3-22:
Data-link layer service definition – Type 22 elements
IEC 61158-4-22, Industrial communication networks – Fieldbus specifications – Part 4-22:
Data-link layer protocol specification – Type 22 elements
IEC 61158-5-22, Industrial communication networks – Fieldbus specifications – Part 5-22:
Application layer service definition – Type 22 elements
IEC 61158-6-22, Industrial communication networks – Fieldbus specifications – Part 6-22:
Application layer protocol specification – Type 22 elements
IEC 61508 (all parts), Functional safety of electrical/electronic/programmable electronic
safety-related systems
___________
In the following pages of this standard, “this part” will be used for “this part of the IEC 61784-3 series”.
In the following pages of this standard, “IEC 61508” will be used for “IEC 61508 series”.

61784-3-18  IEC:2011 – 11 –
IEC 61508-2:2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 2: Requirements for electrical/electronic/programmable electronic
safety-related systems
IEC 61784-2:2010, Industrial communication networks – Profiles – Part 2: Additional fieldbus
profiles for real-time networks based on ISO/IEC 8802-3
IEC 61784-3:2010, Industrial communication networks – Profiles – Part 3: Functional safety
fieldbuses – General rules and profile definitions
IEC 61918, Industrial communication networks – Installation of communication networks in
industrial premises
ISO/IEC 10731, Information technology – Open system interconnection – Basic reference
model – Conventions for the definition of OSI services
3 Terms, definitions, symbols, abbreviated terms and conventions
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1 Common terms and definitions
3.1.1.1
availability
probability for an automated system that for a given period of time there are no unsatisfactory
system conditions such as loss of production
3.1.1.2
black channel
communication channel without available evidence of design or validation according to
IEC 61508
3.1.1.3
communication channel
logical connection between two end-points within a communication system
3.1.1.4
communication system
arrangement of hardware, software and propagation media to allow the transfer of messages
(ISO/IEC 7498 application layer) from one application to another
3.1.1.5
connection
logical binding between two application objects within the same or different devices
3.1.1.6
Cyclic Redundancy Check (CRC)
redundant data derived from, and stored or transmitted together with, a block of data
in order to detect data corruption
procedure used to calculate the redundant data
NOTE 1 Terms “CRC code” and "CRC signature", and labels such as CRC1, CRC2, may also be used in this
standard to refer to the redundant data.

– 12 – 61784-3-18  IEC:2011
NOTE 2 See also [35], [36] .
3.1.1.7
error
discrepancy between a computed, observed or measured value or condition and the true,
specified or theoretically correct value or condition
[IEC 61508-4:2010], [IEC 61158]
NOTE 1 Errors may be due to design mistakes within hardware/software and/or corrupted information due to
electromagnetic interference and/or other effects.
NOTE 2 Errors do not necessarily result in a failure or a fault.
3.1.1.8
failure
termination of the ability of a functional unit to perform a required function or operation of a
functional unit in any way other than as required
NOTE 1 The definition in IEC 61508-4 is the same, with additional notes.
[IEC 61508-4:2010, modified], [ISO/IEC 2382-14.01.11, modified]
NOTE 2 Failure may be due to an error (for example, problem with hardware/software design or message
disruption).
3.1.1.9
fault
abnormal condition that may cause a reduction in, or loss of, the capability of a functional unit
to perform a required function
NOTE IEV 191-05-01 defines “fault” as a state characterized by the inability to perform a required function,
excluding the inability during preventive maintenance or other planned actions, or due to lack of external
resources.
[IEC 61508-4:2010, modified], [ISO/IEC 2382-14.01.10, modified]
3.1.1.10
fieldbus
communication system based on serial data transfer and used in industrial automation or
process control applications
3.1.1.11
frame
denigrated synonym for DLPDU
3.1.1.12
Frame Check Sequence (FCS)
redundant data derived from a block of data within a DLPDU (frame), using a hash function,
and stored or transmitted together with the block of data, in order to detect data corruption
NOTE 1 An FCS can be derived using for example a CRC or other hash function.
NOTE 2 See also [35], [36].
3.1.1.13
hash function
(mathematical) function that maps values from a (possibly very) large set of values into a
(usually) smaller range of values
___________
Figures in square brackets refer to the Bibliography.

61784-3-18  IEC:2011 – 13 –
NOTE 1 Hash functions can be used to detect data corruption.
NOTE 2 Common hash functions include parity, checksum or CRC.
[IEC/TR 62210, modified]
3.1.1.14
hazard
state or set of conditions of a system that, together with other related conditions will inevitably
lead to harm to persons, property or environment
3.1.1.15
message
ordered series of octets intended to convey information
[ISO/IEC 2382-16.02.01, modified]
3.1.1.16
message sink
part of a communication system in which messages are considered to be received
[ISO/IEC 2382-16.02.03]
3.1.1.17
message source
part of a communication system from which messages are considered to originate
[ISO/IEC 2382-16.02.02]
3.1.1.18
nuisance trip
spurious trip with no harmful effect
NOTE Internal abnormal errors can be caused in communication systems such as wireless transmission, for
example by too many retries in the presence of interferences.
3.1.1.19
performance level (PL)
discrete level used to specify
...