SIST EN 61784-3:2017

SLOVENSKI STANDARD
01-marec-2017
1DGRPHãþD
SIST EN 61784-3:2010
Industrijska komunikacijska omrežja - Profili - 3. del: Funkcionalno varna procesna
vodila - Splošna pravila in definicije profilov (IEC 61784-3:2016)
Industrial communication networks - Profiles - Part 3: Functional safety fieldbuses -
General rules and profile definitions (IEC 61784-3:2016)
Industrielle Kommunikationsnetze - Profile - Teil 3: Funktional sichere Übertragung bei
Feldbussen - Allgemeine Regeln und Festlegungen für Profile (IEC 61784-3:2016)
Réseaux de communication industriels - Profils - Partie 3: Bus de terrain de sécurité
fonctionnelle - Règles générales et définitions de profils (IEC 61784-3:2016)
Ta slovenski standard je istoveten z: EN 61784-3:2016
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
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2016
ICS 25.040.40; 35.100.05 Supersedes EN 61784-3:2010
English Version
Industrial communication networks - Profiles -
Part 3: Functional safety fieldbuses -
General rules and profile definitions
(IEC 61784-3:2016)
Réseaux de communication industriels - Profils -  Industrielle Kommunikationsnetze - Profile -
Partie 3: Bus de terrain de sécurité fonctionnelle - Teil 3: Funktional sichere Übertragung bei Feldbussen -
Règles générales et définitions de profils Allgemeine Regeln und Festlegungen für Profile
(IEC 61784-3:2016) (IEC 61784-3:2016)
This European Standard was approved by CENELEC on 2016-06-17. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61784-3:2016 E
European foreword
The text of document 65C/840/FDIS, future edition 3 of IEC 61784-3, 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 approved by CENELEC as EN 61784-3:2016.
The following dates are fixed:
(dop) 2017-03-17
• latest date by which the document has to be implemented at
national level by publication of an identical national
standard or by endorsement
(dow) 2019-06-17
• latest date by which the national standards conflicting with
the document have to be withdrawn

This document supersedes EN 61784-3:2010.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 61784-3:2016 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.
IEC 61131-2:2007 NOTE Harmonized as EN 61131-2:2007 (not modified).
IEC 61131-6 NOTE Harmonized as EN 61131-6.
IEC 61496 NOTE Harmonized in EN 61496 series.
IEC 61496-1 NOTE Harmonized as EN 61496-1.
IEC 61508-4:2010 NOTE Harmonized as EN 61508-4:2010 (not modified).
IEC 61508-5:2010 NOTE Harmonized as EN 61508-5:2010 (not modified).
IEC 61511 NOTE Harmonized in EN 61511 series.
IEC 61800-5-2 NOTE Harmonized as EN 61800-5-2.
IEC 62061:2005 NOTE Harmonized as EN 62061:2005 (not modified).
IEC/TR 62685 NOTE Harmonized as CLC/TR 62685.
ISO 10218-1 NOTE Harmonized as EN ISO 10218-1.
ISO 12100 NOTE Harmonized as EN ISO 12100.
ISO 13849 NOTE Harmonized in EN ISO 13849 series.
ISO 13849-1:2015 NOTE Harmonized as EN ISO 13849-1:2015 (not modified).
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is
available here: www.cenelec.eu.

Publication Year Title EN/HD Year
IEC 61000-6-7 -  Electromagnetic compatibility (EMC) - EN 61000-6-7 -
Part 6-7: Generic standards - Immunity
requirements for equipment intended to
perform functions in a safety-related
system (functional safety) in industrial
locations
IEC 61010-2-201 2013 Safety requirements for electrical EN 61010-2-201 2013
equipment for measurement, control and
- -  + AC 2013
laboratory use -
Part 2-201: Particular requirements for
control equipment
IEC 61158 series Industrial communication networks - EN 61158 series
Fieldbus specifications
IEC 61326-3-1 -  Electrical equipment for measurement, EN 61326-3-1 -
control and laboratory use - EMC
requirements -
Part 3-1: Immunity requirements for
safety-related systems and for
equipment intended to perform safety-
related functions (functional safety) -
General industrial applications
IEC 61326-3-2 -  Electrical equipment for measurement, EN 61326-3-2 -
control and laboratory use - EMC
requirements -
Part 3-2: Immunity requirements for
safety-related systems and for
equipment intended to perform safety-
related functions (functional safety) -
Industrial applications with specified
electromagnetic environment
IEC 61508 series Functional safety of EN 61508 series
electrical/electronic/programmable
electronic safety-related systems
Publication Year Title EN/HD Year
IEC 61508-1 2010 Functional safety of EN 61508-1 2010
electrical/electronic/programmable
electronic safety-related systems -
Part 1: General requirements
IEC 61508-2 -  Functional safety of EN 61508-2 -
electrical/electronic/programmable
electronic safety-related systems -
Part 2: Requirements for
electrical/electronic/programmable
electronic safety-related systems
IEC 61784-1 -  Industrial communication networks - EN 61784-1 -
Profiles -
Part 1: Fieldbus profiles
IEC 61784-2 -  Industrial communication networks - EN 61784-2 -
Profiles -
Part 2: Additional fieldbus profiles for
real-time networks based on
ISO/IEC 8802-3
IEC 61784-3-1 -  Industrial communication networks - EN 61784-3-1 -
Profiles -
Part 3-1: Functional safety fieldbuses -
Additional specifications for CPF 1
IEC 61784-3-2 -  Industrial communication networks - EN 61784-3-2 -
Profiles -
Part 3-2: Functional safety fieldbuses -
Additional specifications for CPF 2
IEC 61784-3-3 -  Industrial communication networks - EN 61784-3-3 -
Profiles -
Part 3-3: Functional safety fieldbuses -
Additional specifications for CPF 3
IEC 61784-3-6 -  Industrial communication networks - EN 61784-3-6 -
Profiles -
Part 3-6: Functional safety fieldbuses -
Additional specifications for CPF 6
IEC 61784-3-8 -  Industrial communication networks - EN 61784-3-8 -
Profiles -
Part 3-8: Functional safety fieldbuses -
Additional specifications for CPF 8
IEC 61784-3-12 -  Industrial communication networks - EN 61784-3-12 -
Profiles -
Part 3-12: Functional safety fieldbuses -
Additional specifications for CPF 12
IEC 61784-3-13 -  Industrial communication networks - EN 61784-3-13 -
Profiles -
Part 3-13: Functional safety fieldbuses -
Additional specifications for CPF 13
IEC 61784-3-14 -  Industrial communication networks - EN 61784-3-14 -
Profiles -
Part 3-14: Functional safety fieldbuses -
Additional specifications for CPF 14
Publication Year Title EN/HD Year
1)
IEC 61784-3-17 -  Industrial communication networks - - -
Profiles -
Part 3-17: Functional safety fieldbuses -
Additional specifications for CPF 17
IEC 61784-3-18 -  Industrial communication networks - EN 61784-3-18 -
Profiles -
Part 3-18: Functionnal safety
fieldbuses - Additional specifications for
CPF 18
IEC 61784-5 series Industrial communication networks - EN 61784-5 series
Profiles -
Part 5: Installation of fieldbuses
IEC 61918 (mod) 2013 Industrial communication networks - EN 61918 2013
Installation of communication networks
- -  + AC 2014
in industrial premises
IEC 62443 series Industrial communication networks - EN 62443 series
Network and system security
1) To be published.
IEC 61784-3 ®
Edition 3.0 2016-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Profiles –

Part 3: Functional safety fieldbuses – General rules and profile definitions

Réseaux de communication industriels – Profils –

Partie 3: Bus de terrain de sécurité fonctionnelle – Règles générales et

définitions de profils
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 35.100.05 ISBN 978-2-8322-3238-5

– 2 – IEC 61784-3:2016  IEC 2016
CONTENTS
FOREWORD . 7
0 Introduction . 9
0.1 General . 9
0.2 Transition from Edition 2 to extended assessment methods in Edition 3 . 11
0.3 Patent declaration . 12
1 Scope . 13
2 Normative references. 13
3 Terms, definitions, symbols, abbreviated terms and conventions. 15
3.1 Terms and definitions . 15
3.2 Symbols and abbreviated terms . 22
4 Conformance . 23
5 Basics of safety-related fieldbus systems . 23
5.1 Safety function decomposition . 23
5.2 Communication system . 24
5.2.1 General . 24
5.2.2 IEC 61158 fieldbuses . 24
5.2.3 Communication channel types . 25
5.2.4 Safety function response time . 25
5.3 Communication errors . 26
5.3.1 General . 26
5.3.2 Corruption . 26
5.3.3 Unintended repetition . 26
5.3.4 Incorrect sequence . 26
5.3.5 Loss . 27
5.3.6 Unacceptable delay . 27
5.3.7 Insertion . 27
5.3.8 Masquerade . 27
5.3.9 Addressing. 27
5.4 Deterministic remedial measures . 27
5.4.1 General . 27
5.4.2 Sequence number . 27
5.4.3 Time stamp . 27
5.4.4 Time expectation . 28
5.4.5 Connection authentication . 28
5.4.6 Feedback message . 28
5.4.7 Data integrity assurance . 28
5.4.8 Redundancy with cross checking . 28
5.4.9 Different data integrity assurance systems . 29
5.5 Typical relationships between errors and safety measures . 29
5.6 Communication phases . 30
5.7 FSCP implementation aspects . 31
5.8 Data integrity considerations . 31
5.8.1 Calculation of the residual error rate . 31
5.8.2 Total residual error rate and SIL . 33
5.9 Relationship between functional safety and security . 34
5.10 Boundary conditions and constraints . 35

IEC 61784-3:2016  IEC 2016 – 3 –
5.10.1 Electrical safety . 35
5.10.2 Electromagnetic compatibility (EMC) . 35
5.11 Installation guidelines . 36
5.12 Safety manual . 36
5.13 Safety policy . 36
6 Communication Profile Family 1 (FOUNDATION™ Fieldbus) – Profiles for functional
safety . 37
7 Communication Profile Family 2 (CIP™) and Family 16 (SERCOS®) – Profiles for
functional safety . 37
8 Communication Profile Family 3 (PROFIBUS™, PROFINET™) – Profiles for
functional safety . 37
9 Communication Profile Family 6 (INTERBUS®) – Profiles for functional safety . 38
10 Communication Profile Family 8 (CC-Link™) – Profiles for functional safety . 38
10.1 Functional Safety Communication Profile 8/1 . 38
10.2 Functional Safety Communication Profile 8/2 . 39
11 Communication Profile Family 12 (EtherCAT™) – Profiles for functional safety . 39
12 Communication Profile Family 13 (Ethernet POWERLINK™) – Profiles for
functional safety . 40
13 Communication Profile Family 14 (EPA®) – Profiles for functional safety . 40
14 Communication Profile Family 17 (RAPIEnet™) – Profiles for functional safety . 40
15 Communication Profile Family 18 (SafetyNET p™ Fieldbus) – Profiles for
functional safety . 41
Annex A (informative) Example functional safety communication models . 42
A.1 General . 42
A.2 Model A (single message, channel and FAL, redundant SCLs) . 42
A.3 Model B (full redundancy) . 42
A.4 Model C (redundant messages, FALs and SCLs, single channel) . 43
A.5 Model D (redundant messages and SCLs, single channel and FAL) . 43
Annex B (normative) Safety communication channel model using CRC-based error
checking . 45
B.1 Overview. 45
B.2 Channel model for calculations . 45
B.3 Bit error probability Pe. 46
B.4 Cyclic redundancy checking . 47
B.4.1 General . 47
B.4.2 Considerations concerning CRC polynomials . 48
Annex C (informative) Structure of technology-specific parts . 50
Annex D (informative) Assessment guideline . 52
D.1 Overview. 52
D.2 Channel types . 52
D.2.1 General . 52
D.2.2 Black channel . 52
D.2.3 White channel . 52
D.3 Data integrity considerations for white channel approaches . 53
D.3.1 General . 53
D.3.2 Models B and C . 53
D.3.3 Models A and D . 54
D.4 Verification of safety measures . 55

– 4 – IEC 61784-3:2016  IEC 2016
D.4.1 General . 55
D.4.2 Implementation . 55
D.4.3 "De-energize to trip" principle . 55
D.4.4 Safe state . 55
D.4.5 Transmission errors . 55
D.4.6 Safety reaction and response times . 55
D.4.7 Combination of measures . 56
D.4.8 Absence of interference . 56
D.4.9 Additional fault causes (white channel) . 56
D.4.10 Reference test beds and operational conditions . 56
D.4.11 Conformance tester . 56
Annex E (informative) Examples of implicit vs. explicit FSCP safety measures . 57
E.1 General . 57
E.2 Example fieldbus message with safety PDUs . 57
E.3 Model with completely explicit safety measures . 57
E.4 Model with explicit A-code and implicit T-code safety measures . 58
E.5 Model with explicit T-code and implicit A-code safety measures . 58
E.6 Model with split explicit and implicit safety measures . 59
E.7 Model with completely implicit safety measures . 60
E.8 Addition to Annex B – impact of implicit codes on properness . 60
Annex F (informative) Extended models for estimation of the total residual error rate . 61
F.1 Applicability . 61
F.2 General models for black channel communications . 61
F.3 Identification of generic safety properties . 62
F.4 Assumptions for residual error rate calculations . 62
F.5 Residual error rates. 63
F.5.1 Explicit and implicit mechanisms . 63
F.5.2 Residual error rate calculations . 63
F.6 Data integrity . 65
F.6.1 Probabilistic considerations . 65
F.6.2 Deterministic considerations . 65
F.7 Authenticity . 66
F.7.1 General . 66
F.7.2 Residual error rate for authenticity (RR ) . 67
A
F.8 Timeliness . 68
F.8.1 General . 68
F.8.2 Residual error rate for timeliness (RR ) . 70
T
F.9 Masquerade . 71
F.9.1 General . 71
F.9.2 Other terms used to calculate residual error rate for masquerade
rejection (RR ) . 71
M
F.10 Calculation of the total residual error rates . 71
F.10.1 Based on the summation of the residual error rates . 71
F.10.2 Based on other quantitative proofs . 72
F.11 Total residual error rate and SIL . 72
F.12 Configuration and parameterization for an FSCP . 73
F.12.1 General . 73
F.12.2 Configuration and parameterization change rate . 75
F.12.3 Residual error rate for configuration and parameterization . 75

IEC 61784-3:2016  IEC 2016 – 5 –
Bibliography . 76

Figure 1 – Relationships of IEC 61784-3 with other standards (machinery) . 9
Figure 2 – Relationships of IEC 61784-3 with other standards (process) . 10
Figure 3 – Transition from Edition 2 to Edition 3 assessment methods . 11
Figure 4 – Safety communication as a part of a safety function . 24
Figure 5 – Example model of a functional safety communication system . 25
Figure 6 – Example of safety function response time components . 26
Figure 7 – Conceptual FSCP protocol model . 31
Figure 8 – FSCP implementation aspects . 31
Figure 9 – Example application 1 (m=4) . 33
Figure 10 – Example application 2 (m = 2) . 33
Figure 11 – Zones and conduits concept for security according to IEC 62443 . 35
Figure A.1 – Model A . 42
Figure A.2 – Model B . 43
Figure A.3 – Model C . 43
Figure A.4 – Model D . 44
Figure B.1 – Communication channel with perturbation . 45
Figure B.2 – Binary symmetric channel (BSC) . 46
Figure B.3 – Example of a block with a message part and a CRC signature . 47
Figure B.4 – Block codes for error detection . 48
Figure B.5 – Proper and improper CRC polynomials . 49
Figure D.1 – Basic Markov model . 54
Figure E.1 – Example safety PDUs embedded in a fieldbus message . 57
Figure E.2 – Model with completely explicit safety measures . 57
Figure E.3 – Model with explicit A-code and implicit T-code safety measures . 58
Figure E.4 – Model with explicit T-code and implicit A-code safety measures . 59
Figure E.5 – Model with split explicit and implicit safety measures . 59
Figure E.6 – Model with completely implicit safety measures . 60
Figure F.1 – Black channel from an FSCP perspective . 61
Figure F.2 – Model for authentication considerations . 66
Figure F.3 – Fieldbus and internal address errors . 67
Figure F.4 – Example of slowly increasing message latency . 69
Figure F.5 – Example of an active network element failure . 70
Figure F.6 – Example application 1 (m = 4) . 72
Figure F.7 – Example application 2 (m = 2) . 72
Figure F.8 – Example of configuration and parameterization procedures for FSCP . 74

Table 1 – Overview of the effectiveness of the various measures on the possible errors . 30
Table 2 – Definition of items used for calculation of the residual error rates . 32
Table 3 – Typical relationship of residual error rate to SIL. 34
Table 4 – Typical relationship of residual error on demand to SIL . 34
Table 5 – Overview of profile identifier usable for FSCP 6/7 . 38

– 6 – IEC 61784-3:2016  IEC 2016
Table B.1 – Example dependency d and block bit length n . 48
min
Table C.1 – Common subclause structure for technology-specific parts . 50
Table F.1 – Typical relationship of residual error rate to SIL . 73
Table F.2 – Typical relationship of residual error on demand to SIL. 73

IEC 61784-3:2016  IEC 2016 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES –
Part 3: Functional safety fieldbuses –
General rules and profile definitions

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-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
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 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This third edition cancels and replaces the second edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• clarifications and additional explanations for requirements, updated references;
• deletion of technical overviews of profiles (Clauses 6 to 13), and associated dedicated
subclauses for terms, definitions, symbols and abbreviations;
• addition of profiles for Communication Profile Families 8, 17 and 18 (Clauses 10, 14, 15);
• clarifications of models in Annex A;

– 8 – IEC 61784-3:2016  IEC 2016
• Annex B changed from informative to normative;
• addition of a new informative Annex E describing models for explicit and implicit FSCP
mechanisms;
• addition of a new informative Annex F introducing an extended model for estimation of the
total residual error rate;
• updates in parts for CPF 1, CPF 2, CPF 3, CPF 8, CPF 13 (details provided in the parts);
• addition of a new part for CPF 17.
The text of this standard is based on the following documents:
FDIS Report on voting
65C/840/FDIS 65C/848/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.
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 website 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.
IEC 61784-3:2016  IEC 2016 – 9 –
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 fieldbus enhancements continue to emerge, addressing applications for 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.
IEC
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)

– 10 – IEC 61784-3:2016  IEC 2016
Figure 2 shows the relationships between this standard and relevant safety and fieldbus
standards in a process environment.
IEC
a
For specified electromagnetic environments; otherwise IEC 61326-3-1 or IEC 61000-6-7.
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 (FSCP) within this system – implementation of a functional
safety communication profile in a standard device is not sufficient to qualify it as a safety
device.
IEC 61784-3:2016  IEC 2016 – 11 –
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;
• functional safety communication profiles for several communication profile families in
IEC 61784-1 and IEC 61784-2, including safety layer extensions to the communication
service and protocols sections of the IEC 61158 series.
0.2 Transition from Edition 2 to extended assessment methods in Edition 3
This edition of the generic part of the standard includes additional extended models for future
use when estimating the total residual error rate for an FSCP. This value can be used to
determine if the FSCP meets the requirements of functional safety applications up to a given
SIL. These extended models for qualitative and quantitative safety determination methods are
detailed in Annex E and Annex F.
However, because of the typical duration of the assessment process, the FSCPs published
prior to or concurrently with this new edition of the generic part can only be assessed using
the methods from previous editions, based on data integrity considerations specified in 5.8.
The validity schema in Figure 3 shows how to handle the transition from original assessment
methods of Edition 2 (specified in 5.8) to extended assessment methods in Edition 3
(currently specified in Annex F). According to this schema, the FSCPs are exempt from a new
assessment according to Annex F until Edition 4, where the contents of current Annex F will
replace the current 5.8.
NOTE However, a particular FSCP can achieve an earlier assessment and publish an adequate amendment.
IEC
Key
DI Data Integrity
TADI Timeliness, Authenticity, Data Integrity
Figure 3 – Transition from Edition 2 to Edition 3 assessment methods

– 12 – IEC 61784-3:2016  IEC 2016
0.3 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 patents concerning
functional safety communication profiles for families 1, 2, 3, 6, 8, 12, 13, 14, 17 and 18 given
in IEC 61784-3-1, IEC 61784-3-2, IEC 61784-3-3, IEC 61784-3-6, IEC 61784-3-8,
IEC 61784-3-12, IEC 61784-3-13, IEC 61784-3-14, IEC 61784-3-17 and IEC 61784-3-18.
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holders of these patent rights have assured the IEC that they are willing to negotiate
licences either free of charge or und
...