EN 61784-3-8:2010

SLOVENSKI STANDARD
01-oktober-2010
Industrijska komunikacijska omrežja - Profili - 3-8. del: Funkcijska varnost
procesnih vodil - Dodatne specifikacije za CPF 8 (IEC 61784-3-8:2010)
Industrial communication networks - Profiles - Part 3-8: Functional safety fieldbuses -
Additional specifications for CPF 8 (IEC 61784-3-8:2010)
Industrielle Kommunikationsnetze - Profile - Teil 3-8: Funktional sichere Übertragung bei
Feldbussen - Zusätzliche Festlegungen für die Kommunikationsprofilfamilie 8 (IEC 61784
-3-8:2010)
Réseaux de communication industriels - Profils - Partie 3-8: Bus de terrain de sécurité
fonctionnelle - Spécification supplémentaire pour CPF 8 (CEI 61784-3-8:2010)
Ta slovenski standard je istoveten z: EN 61784-3-8:2010
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 61784-3-8
NORME EUROPÉENNE
August 2010
EUROPÄISCHE NORM
ICS 25.040.40; 35.100.05
English version
Industrial communication networks -
Profiles -
Part 3-8: Functional safety fieldbuses -
Additional specifications for CPF 8
(IEC 61784-3-8:2010)
Réseaux de communication industriels -  Industrielle Kommunikationsnetze -
Profils - Profile -
Partie 3-8: Bus de terrain de sécurité Teil 3-8: Funktional sichere Übertragung
fonctionnelle - bei Feldbussen -
Spécification supplémentaire pour CPF 8 Zusätzliche Festlegungen
(CEI 61784-3-8:2010) für die Kommunikationsprofilfamilie 8
(IEC 61784-3-8:2010)
This European Standard was approved by CENELEC on 2010-07-01. 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

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61784-3-8:2010 E
Foreword
The text of document 65C/591A/FDIS, future edition 1 of IEC 61784-3-8, 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 61784-3-8 on 2010-07-01.
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) 2011-04-01
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2013-07-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61784-3-8:2010 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 61496 series NOTE  Harmonized in EN 61496 series (partially modified).
IEC 61508-1:2010 NOTE  Harmonized as EN 61508-1:2010 (not modified).
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 61784-2 NOTE  Harmonized as EN 61784-2.
IEC 61784-5 series NOTE  Harmonized in EN 61784-5 series (not modified).
IEC 61800-5-2 NOTE  Harmonized as EN 61800-5-2.
IEC 61918 NOTE  Harmonized as EN 61918.
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.
ISO 13849-2 NOTE  Harmonized as EN ISO 13849-2.
__________
- 3 - EN 61784-3-8:2010
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 60204-1 - Safety of machinery - Electrical equipment EN 60204-1 -
of machines -
Part 1: General requirements
IEC 61131-2 - Programmable controllers - EN 61131-2 -
Part 2: Equipment requirements and tests

IEC 61158 Series Industrial communication networks - EN 61158 Series
Fieldbus specifications -
IEC 61158-2 - Industrial communication networks – EN 61158-2 -
Fieldbus specifications -
Part 2: Physical layer specification and service
definition
IEC 61158-3-18 - Industrial communication networks - Fieldbus EN 61158-3-18 -
specifications -
Part 3-18: Data-link layer service definition -
Type 18 elements
IEC 61158-4-18 - Industrial communication networks - Fieldbus EN 61158-4-18 -
specifications -
Part 4-18: Data-link layer protocol
specification - Type 18 elements

IEC 61158-5-18 - Industrial communication networks - Fieldbus EN 61158-5-18 -
specifications -
Part 5-18: Application layer service definition -
Type 18 elements
IEC 61158-6-18 - Industrial communication networks - Fieldbus EN 61158-6-18 -
specifications -
Part 6-18: Application layer protocol
specification - Type 18 elements

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

Publication Year Title EN/HD Year

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
IEC 61511 Series Functional safety - Safety instrumented EN 61511 Series
systems for the process industry sector

IEC 61784-1 - Industrial communication networks - Profiles - EN 61784-1 -
Part 1: Fieldbus profiles
IEC 61784-3 2010 Industrial communication networks - Profiles - EN 61784-3 2010
Part 3: Functional safety fieldbuses - General
rules and profile definitions
IEC 62061 - Safety of machinery - Functional safety of EN 62061 -
safety-related electrical, electronic and
programmable electronic control systems

IEC 61784-3-8 ®
Edition 1.0 2010-06
INTERNATIONAL
STANDARD
colour
inside
Industrial communication networks – Profiles –
Part 3-8: Functional safety fieldbuses – Additional specifications for CPF 8

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
X
ICS 25.040.40; 35.100.05 ISBN 978-2-88910-980-7
– 2 – 61784-3-8 © IEC:2010(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7
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 8: Additional terms and definitions .16
3.2 Symbols and abbreviated terms.16
3.2.1 Common symbols and abbreviated terms .16
3.2.2 CPF 8: Additional symbols and abbreviated terms .17
3.3 Conventions .17
4 Overview of FSCP 8/1 (CC-Link Safety™) .17
5 General .18
5.1 External documents providing specifications for the profile.18
5.2 Safety functional requirements .18
5.3 Safety measures .18
5.3.1 General .18
5.3.2 Sequence number .19
5.3.3 Time expectation .19
5.3.4 Connection authentication .20
5.3.5 Feedback message .20
5.3.6 Different data integrity assurance system .20
5.4 Safety communication layer structure .20
5.5 Relationships with FAL (and DLL, PhL) .21
5.5.1 Overview .21
5.5.2 Data types .21
6 Safety communication layer services .21
6.1 General .21
6.2 SASEs.21
6.2.1 M1 safety device manager class specification.21
6.2.2 S1 safety device manager class specification .22
6.3 SARs.22
6.3.1 M1 safety connection manager class .22
6.3.2 S1 safety connection manager class.22
6.4 Process data SAR ASEs.23
6.4.1 M1 safety cyclic transmission class specification .23
6.4.2 S1 safety cyclic transmission class specification.23
7 Safety communication layer protocol .24
7.1 Safety PDU format .24
7.1.1 General .24
7.1.2 Abstract syntax.24
7.1.3 Transfer syntax.26
7.2 State description .30
7.2.1 Overview .30
7.2.2 Idle.31

61784-3-8 © IEC:2010(E) – 3 –
7.2.3 FAL running.31
7.2.4 SCL running .32
7.2.5 Fail safe .32
7.2.6 Safety data transmission and processing.32
7.2.7 Forced termination .34
8 Safety communication layer management.34
8.1 General .34
8.2 Connection establishment and confirmation processing.35
8.3 Safety slave verification .35
8.3.1 General .35
8.3.2 Safety slave information verification process .35
8.3.3 Safety slave parameter transmission .35
9 System requirements.36
9.1 Indicators and switches .36
9.1.1 Switches.36
9.1.2 Indicators .36
9.2 Installation guidelines.37
9.3 Safety function response time .37
9.3.1 General .37
9.3.2 Time calculation .37
9.4 Duration of demands .39
9.5 Constraints for calculation of system characteristics.39
9.5.1 System characteristics.39
9.5.2 Residual error rate (Λ) .39
9.6 Maintenance.40
9.7 Safety manual .40
10 Assessment.41
Annex A (informative) Additional information for functional safety communication
profiles of CPF 8.42
A.1 Hash function calculation.42
A.2 … .42
Annex B (informative) Information for assessment of the functional safety
communication profiles of CPF 8 .43
Bibliography.44

Table 1 – Selection of the various measures for possible errors.19
Table 2 – M1 safety device manager attribute format .24
Table 3 – S1 safety device manager attribute format .24
Table 4 – M1 safety connection manager attribute format .24
Table 5 – S1 safety connection manager attribute format.25
Table 6 – M1 safety cyclic transmission attribute format .25
Table 7 – S1 safety cyclic transmission attribute format .26
Table 8 – M1 safety device manager attribute encoding.26
Table 9 – S1 safety device manager attribute encoding .27
Table 10 – M1 safety connection manager attribute encoding .27
Table 11 – S1 safety connection manager attribute encoding.27

– 4 – 61784-3-8 © IEC:2010(E)
Table 12 – M1 safety cyclic transmission attribute encoding .28
Table 13 – S1 safety cyclic transmission attribute encoding.29
Table 14 – Safety master monitor timer operation .33
Table 15 – Safety slave monitor timer operation .33
Table 16 – Safety data monitor timer operation.33
Table 17 – Details of connection establishment and confirmation processing.35
Table 18 – Details of slave information verification processing.35
Table 19 – Details of safety slave parameter transmission processing .36
Table 20 – Monitor LEDs .36
Table 21 – Safety function response time calculation.38
Table 22 – Safety function response time definition of terms.38
Table 23 – Number of occupied slots and safety data .39
Table 24 – Residual error rate Λ (occupied slots = 1).40
Table 25 – Residual error rate Λ (occupied slots = 2).40

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 – Relationship between SCL and the other layers of IEC 61158 Type 18.21
Figure 4 – State diagram .31

61784-3-8 © IEC:2010(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES –
Part 3-8: Functional safety fieldbuses –
Additional specifications for CPF 8

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 61784-3-8 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial process measurement, control and
automation.
The text of this standard is based on the following documents:
FDIS Report on voting
65C/591A/FDIS 65C/603/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 – 61784-3-8 © IEC:2010(E)
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.
61784-3-8 © IEC:2010(E) – 7 –
INTRODUCTION
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
IEC 61496 IEC 61800-5-2 ISO 10218-1 Safety of machinery – Principles for
IEC 61496 IEC 61131-6 IEC 61800-5-2 ISO 10218-1 Safety of machinery – Principles for
IEC 61131-6
design and risk assessment
Safety f. e.g. Safety for PLC Safety functions Safety requirements
Safety f. e.g. 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
Design objective
Installation guide Installation guide
(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 61784-3 IEC 61326-3-1
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
profiles US: NFPA 79
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
(SRECS)
IEC 61784-1, -2 IEC 61508 series
(SRECS)
Functional safety (FS)
Fieldbus for use in (including EMC for
Functional safety (FS)
Fieldbus for use in (including EMC for
(basic standard)
industrial environment)
industrial control systems (basic standard)
industrial environment)
industrial control systems
Key
(yellow) safety-related standards
(blue) fieldbus-related standards
(dashed yellow) this standard
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 – 61784-3-8 © IEC:2010(E)
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
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.

61784-3-8 © IEC:2010(E) – 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.
– 10 – 61784-3-8 © IEC:2010(E)
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES –
Part 3-8: Functional safety fieldbuses –
Additional specifications for CPF 8

1 Scope
This part of the IEC 61784-3 series specifies a safety communication layer (services and
protocol) based on CPF 8 of IEC 61784-1 and IEC 61158 Type 18. 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 60204-1, Safety of machinery – Electrical equipment of machines – Part 1: General
requirements
IEC 61131-2, Programmable controllers – Part 2: Equipment requirements and tests
IEC 61158 (all parts), Industrial communication networks – Fieldbus specifications
IEC 61158-2, Industrial communication networks – Fieldbus specifications – Part 2: Physical
layer specification and service definition
IEC 61158-3-18, Industrial communication networks – Fieldbus specifications – Part 3-18:
Data-link layer service definition – Type 18 elements
IEC 61158-4-18, Industrial communication networks – Fieldbus specifications – Part 4-18:
Data-link layer protocol specification – Type 18 elements
—————————
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”.

61784-3-8 © IEC:2010(E) – 11 –
IEC 61158-5-18, Industrial communication networks – Fieldbus specifications – Part 5-18:
Application layer service definition – Type 18 elements
IEC 61158-6-18, Industrial communication networks – Fieldbus specifications – Part 6-18:
Application layer protocol specification – Type 18 elements
IEC 61326-3-1, Electrical equipment for measurement, 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, 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 (all parts), Functional safety of electrical/electronic/programmable electronic
safety-related systems
IEC 61511 (all parts), Functional safety – Safety instrumented systems for the process
industry sector
IEC 61784-1, Industrial communication networks – Profiles – Part 1: Fieldbus profiles
IEC 61784-3: 2010 Industrial communication networks – Profiles – Part 3: Functional safety
fieldbuses – General rules and profile definitions
IEC 62061, Safety of machinery – Functional safety of safety-related electrical, electronic and
programmable electronic control systems
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
—————————
In preparation.
– 12 – 61784-3-8 © IEC:2010(E)
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.
NOTE 2 See also [32], [33] .
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
—————————
Figures in square brackets refer to the bibliography.
To be published.
61784-3-8 © IEC:2010(E) – 13 –
3.1.1.11
frame
denigrated synonym for DLPDU
3.1.1.12
hash function
(mathematical) function that maps values from a (possibly very) large set of values into a
(usually) smaller range of values
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]
3.1.1.13
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
3.1.1.14
master
active communication entity able to initiate and schedule communication activities by other
stations which may be masters or slaves
3.1.1.15
message
ordered series of octets intended to convey information
[ISO/IEC 2382-16.02.01, modified]
3.1.1.16
performance level (PL)
discrete level used to specify the ability of safety-related parts of control systems to perform a
safety function under foreseeable conditions
[ISO 13849-1]
3.1.1.17
protective extra-low-voltage (PELV)
electrical circuit in which the voltage cannot exceed a.c. 30 V r.m.s., 42,4 V peak or d.c. 60 V
in normal and single-fault condition, except earth faults in other circuits
NOTE A PELV circuit is similar to an SELV circuit that is connected to protective earth.
[IEC 61131-2]
3.1.1.18
redundancy
existence of means, in addition to the means which would be sufficient for a functional unit to
perform a required function or for data to represent information
NOTE The definition in IEC 61508-4 is the same, with additional example and notes.
[IEC 61508-4:2010, modified], [ISO/IEC 2382-14.01.12, modified]
3.1.1.19
reliability
probability that an automated system can perform a required function under given conditions
for a given time interval (t1,t2)
NOTE 1 It is generally assumed that the automated system is in a state to perform this required function at the
beginning of the time interval.

– 14 – 61784-3-8 © IEC:2010(E)
NOTE 2 The term "reliability" is also used to denote the reliability performance quantified by this probability.
NOTE 3 Within the MTBF or MTTF period of time, the probability that an automated system will perform a
required function under given conditions is decreasing.
NOTE 4 Reliability differs from availability.
[IEC 62059-11, modified]
3.1.1.20
risk
combination of the probability of occurrence of harm and the severity of that harm
NOTE For more discussion on this concept see Annex A of IEC 61508-5:2010 .
[IEC 61508-4:2010], [ISO/IEC Guide 51:1999, definition 3.2]
3.1.1.21
safety communication layer (SCL)
communication layer that includes all the necessary measures to ensure safe transmission of
data in accordance with the requirements of IEC 61508
3.1.1.22
safety connection
connection that utilizes the safety protocol for communications transactions
3.1.1.23
safety data
data transmitted across a safety network using a safety protocol
NOTE The Safety Communication Layer does not ensure safety of the data itself, only that the data is transmitted
safely.
3.1.1.24
safety device
device designed in accordance with IEC 61508 and which implements the functional safety
communication profile
3.1.1.25
safety extra-low-voltage (SELV)
electrical circuit in which the voltage cannot exceed a.c. 30 V r.m.s., 42,4 V peak or d.c. 60 V
in normal and single-fault condition, including earth faults in other circuits
NOTE An SELV circuit is not connected to protective earth.
[IEC 61131-2]
3.1.1.26
safety function
fun
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