IEC 61784-3:2010

IEC 61784-3 ®
Edition 2.0 2010-06
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
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IEC 61784-3 ®
Edition 2.0 2010-06
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
PRICE CODE
INTERNATIONALE
XA
CODE PRIX
ICS 25.040.40; 35.100.05 ISBN 978-2-88912-810-5
– 2 – 61784-3  IEC:2010
CONTENTS
FOREWORD . 6
0 Introduction . 8
0.1 General . 8
0.2 Patent declaration . 10
1 Scope . 11
2 Normative references . 11
3 Terms, definitions, symbols, abbreviated terms and conventions . 13
3.1 Terms and definitions . 13
3.1.1 Common terms and definitions . 13
3.1.2 CPF 1: Additional terms and definitions . 18
3.1.3 CPF 2: Additional terms and definitions . 18
3.1.4 CPF 3: Additional terms and definitions . 18
3.1.5 CPF 6: Additional terms and definitions . 18
3.1.6 CPF 8: Additional terms and definitions . 18
3.1.7 CPF 12: Additional terms and definitions . 18
3.1.8 CPF 13: Additional terms and definitions . 18
3.1.9 CPF 14: Additional terms and definitions . 18
3.2 Symbols and abbreviated terms. 19
3.2.1 Common symbols and abbreviated terms . 19
3.2.2 CPF 1: Additional symbols and abbreviated terms . 19
3.2.3 CPF 2: Additional symbols and abbreviated terms . 19
3.2.4 CPF 3: Additional symbols and abbreviated terms . 19
3.2.5 CPF 6: Additional symbols and abbreviated terms . 20
3.2.6 CPF 8: Additional symbols and abbreviated terms . 20
3.2.7 CPF 12: Additional symbols and abbreviated terms . 20
3.2.8 CPF 13: Additional symbols and abbreviated terms . 20
3.2.9 CPF 14: Additional symbols and abbreviated terms . 20
4 Conformance . 20
5 Basics of safety-related fieldbus systems . 21
5.1 Safety function decomposition . 21
5.2 Communication system . 21
5.2.1 General . 21
5.2.2 IEC 61158 fieldbuses . 21
5.2.3 Communication channel types . 22
5.2.4 Safety function response time . 22
5.3 Communication errors . 23
5.3.1 General . 23
5.3.2 Corruption . 23
5.3.3 Unintended repetition . 23
5.3.4 Incorrect sequence . 23
5.3.5 Loss . 24
5.3.6 Unacceptable delay . 24
5.3.7 Insertion . 24
5.3.8 Masquerade . 24
5.3.9 Addressing . 24
5.4 Deterministic remedial measures . 24

61784-3  IEC:2010 – 3 –
5.4.1 General . 24
5.4.2 Sequence number . 25
5.4.3 Time stamp . 25
5.4.4 Time expectation . 25
5.4.5 Connection authentication . 25
5.4.6 Feedback message . 25
5.4.7 Data integrity assurance . 25
5.4.8 Redundancy with cross checking . 25
5.4.9 Different data integrity assurance systems . 26
5.5 Relationships between errors and safety measures . 26
5.6 Data integrity considerations . 27
5.6.1 Calculation of the residual error rate . 27
5.6.2 Residual error rate and SIL . 29
5.7 Relationship between functional safety and security . 29
5.8 Boundary conditions and constraints . 30
5.8.1 Electrical safety . 30
5.8.2 Electromagnetic compatibility (EMC) . 30
5.9 Installation guidelines . 30
5.10 Safety manual . 30
5.11 Safety policy . 30
6 Communication Profile Family 1 (FOUNDATION™ Fieldbus) – Profiles for functional
safety . 31
6.1 Functional Safety Communication Profile 1/1 . 31
6.2 Technical overview . 31
7 Communication Profile Family 2 (CIP™) – Profiles for functional safety . 32
7.1 Functional Safety Communication Profile 2/1 . 32
7.2 Technical overview . 32
8 Communication Profile Family 3 (PROFIBUS™, PROFINET™) – Profiles for
functional safety . 34
8.1 Functional Safety Communication Profile 3/1 . 34
8.2 Technical overview . 34
9 Communication Profile Family 6 (INTERBUS®) – Profiles for functional safety . 36
9.1 Functional Safety Communication Profile 6/7 . 36
9.2 Technical overview . 37
10 Communication Profile Family 8 (CC-Link™) – Profiles for functional safety . 38
10.1 Functional Safety Communication Profile 8/1 . 38
10.2 Technical overview . 38
11 Communication Profile Family 12 (EtherCAT™) – Profiles for functional safety . 39
11.1 Functional Safety Communication Profile 12/1 . 39
11.2 Technical overview . 39
12 Communication Profile Family 13 (Ethernet POWERLINK™) – Profiles for
functional safety . 40
12.1 Functional Safety Communication Profile 13/1 . 40
12.2 Technical overview . 40
13 Communication Profile Family 14 (EPA®) – Profiles for functional safety . 41
13.1 Functional Safety Communication Profile 14/1 . 41
13.2 Technical overview . 42
Annex A (informative) Example functional safety communication models . 43

– 4 – 61784-3  IEC:2010
A.1 General . 43
A.2 Model A . 43
A.3 Model B . 43
A.4 Model C . 44
A.5 Model D . 44
Annex B (informative) A safety communication channel model using CRC-based error
checking . 46
B.1 Overview . 46
B.2 Channel model for calculations . 46
B.3 Cyclic redundancy checking . 47
B.3.1 General . 47
B.3.2 Considerations concerning CRC polynomials . 49
Annex C (informative) Structure of technology-specific parts . 51
Annex D (informative) Assessment guideline . 53
D.1 Overview . 53
D.2 Channel types . 53
D.2.1 General . 53
D.2.2 Black channel . 53
D.2.3 White channel . 53
D.3 Data integrity considerations for white channel approaches . 54
D.3.1 General . 54
D.3.2 Model B and C . 54
D.3.3 Model A and D . 55
D.4 Verification of safety measures . 55
D.4.1 General . 55
D.4.2 Implementation . 56
D.4.3 "De-energize to trip" principle . 56
D.4.4 Safe state . 56
D.4.5 Transmission errors . 56
D.4.6 Safety reaction and response times . 56
D.4.7 Combination of measures . 56
D.4.8 Absence of interference . 57
D.4.9 Additional fault causes (white channel) . 57
D.4.10 Reference test beds and operational conditions . 57
D.4.11 Conformance tester . 57
Bibliography . 58

Table 1 – Overview of the effectiveness of the various measures on the possible errors . 27
Table 2 – Definition of items used for calculation of the residual error rate . 28
Table 3 – Relationship of residual error rate to SIL level . 29
Table 4 – Overview of profile identifier usable for FSCP 6/7. 37
Table B.1 – Example dependency d and block length n . 49
min
Table C.1 – Common subclause structure for technology-specific parts . 51

61784-3  IEC:2010 – 5 –
Figure 1 – Relationships of IEC 61784-3 with other standards (machinery) . 8
Figure 2 – Relationships of IEC 61784-3 with other standards (process) . 9
Figure 3 – Safety communication as a part of a safety function . 21
Figure 4 – Example model of a functional safety communication system . 22
Figure 5 – Example of safety function response time components . 23
Figure 6 – Example application . 29
Figure 7 – Scope of FSCP 1/1 . 32
Figure 8 – Relationship of Safety Validators . 33
Figure 9 – Basic communication preconditions for FSCP 3/1 . 35
Figure 10 – Structure of a FSCP 3/1 safety PDU . 35
Figure 11 – Safe communication modes. 36
Figure 12 – FSCP 6/7 communication preconditions . 37
Figure 13 – Basic FSCP 12/1 system . 39
Figure 14 – Producer consumer example . 41
Figure 15 – Client server example . 41
Figure 16 – FSCP 14/1 safety communication architecture . 42
Figure A.1 – Model A . 43
Figure A.2 – Model B . 44
Figure A.3 – Model C . 44
Figure A.4 – Model D . 45
Figure B.1 – Communication channel with perturbation . 46
Figure B.2 – Binary symmetric channel (BSC) . 47
Figure B.3 – Example of a block with message and CRC bits (redundancy code) . 48
Figure B.4 – Block codes for error detection . 48
Figure B.5 – Proper and improper CRC polynomials . 49
Figure D.1 – Basic Markov model . 55

– 6 – 61784-3  IEC:2010
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,
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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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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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 second edition cancels and replaces the first edition published in 2007. This edition
constitutes a technical revision. The main changes with respect to the previous edition are
listed below:
– clarifications and additional explanations for requirements, updated references;
– updates of definitions and requirements in relation with the new edition of IEC 61508;
– addition of a new informative Annex D providing an assessment guideline;
– updates in parts for CPF 1, CPF 2, CPF 3, CPF 6 (details provided in the parts);
– addition of new parts for CPF 8, CPF 12, CPF 13, CPF 14;
– in CPF parts, addition of an annex to provide information about test laboratories for
testing and validating conformance of FSCP products.

61784-3  IEC:2010 – 7 –
This bilingual version published in 2011-12, corresponds to the English version published
in 2010-07.
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.
The French version of this standard has not been voted upon.
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 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.
– 8 – 61784-3  IEC:2010
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
IEC 61496 IEC 61800-5-2 ISO 10218-1 Safety of machinery – Principles for
IEC 61131-6
IEC 61496 IEC 61131-6 IEC 61800-5-2 ISO 10218-1 Safety of machinery – Principles for
Safety f. e.g. Safety functions Safety requirements design and risk assessment
Safety for PLC design and risk assessment
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
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
(SRPCS)
Methodology EMC & FS
(SRPCS)
IEC 61784-3 IEC 61326-3-1
IEC 61784-3 IEC 61326-3-1
Non-electrical
Non-electrical
Functional safety Test EMC & FS
Test EMC & FS
Functional safety
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
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)

61784-3  IEC:2010 – 9 –
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.

– 10 – 61784-3  IEC:2010
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 patents concerning
functional safety communication profiles for families 1, 2, 3, 6, 12, 13 and 14 given in
IEC 61784-3-1, IEC 61784-3-2, IEC 61784-3-3, IEC 61784-3-6, IEC 61784-3-12,
IEC 61784-3-13 and IEC 61784-3-14.
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holders of these patent rights have assured IEC that they are willing to negotiate licences
under reasonable and non-discriminatory terms and conditions with applicants throughout the
world. In this respect, the statements of the holders of these patent rights are registered with
IEC.
NOTE Patent details and corresponding contact information are provided in IEC 61784-3-1, IEC 61784-3-2,
IEC 61784-3-3, IEC 61784-3-6, IEC 61784-3-12, IEC 61784-3-13 and IEC 61784-3-14.

61784-3  IEC:2010 – 11 –
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES –
Part 3: Functional safety fieldbuses –
General rules and profile definitions

1 Scope
This part of the IEC 61784-3 series explains some common principles than can be used in 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 principles can be used in various industrial applications such as
process control, manufacturing automation and machinery.
This part and the IEC 61784-3-x parts specify several functional safety communication
profiles based on the communication profiles and protocol layers of the fieldbus technologies
in IEC 61784-1, IEC 61784-2 and the IEC 61158 series.
NOTE 1 Other safety-related communication systems meeting the requirements of IEC 61508 series may exist
that are not included in this standard.
NOTE 2 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.
All systems are exposed to unauthorized access at some point of their life cycle. Additional
measures need to be considered in any safety-related application to protect fieldbus systems
against unauthorized access. The IEC 62443 series will address many of these issues; the
relationship with the IEC 62443 series is detailed in a dedicated subclause of this part.
NOTE 3 Additional profile specific requirements for security may also be specified in IEC 61784-4 [10].
NOTE 4 Implementation of a functional safety communication profile according to this part in a device is not
sufficient to qualify it as a safety device, as defined in IEC 61508 series.
NOTE 5 The resulting SIL claim of a system depends on the implementation of the selected functional safety
communication profile within this system.
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 61131-2, Programmable controllers – Part 2: Equipment requirements and tests
IEC 61158 (all parts), Industrial communication networks – Fieldbus specifications
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
—————————
In the following pages of this standard, “IEC 61508” will be used for “IEC 61508 series”.
In the following pages of this standard, “this part” will be used for “this part of the IEC 61784-3 series”.
Proposed new work item under consideration.

– 12 – 61784-3  IEC:2010
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 61508-1:2010 , Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 1: General requirements
IEC 61508-2, Functional safety of electrical/electronic/programmable electronic safety-related
systems – Part 2: Requirements for electrical/electronic/programmable electronic safety-
related systems
IEC 61784-1, Industrial communication networks – Profiles – Part 1: Fieldbus profiles
IEC 61784-2, Industrial communication networks – Profiles – Part 2: Additional fieldbus
profiles for real-time networks based on ISO/IEC 8802-3
IEC 61784-3-1, Industrial communication networks – Profiles – Part 3-1: Functional safety
fieldbuses – Additional specifications for CPF 1
IEC 61784-3-2, Industrial communication networks – Profiles – Part 3-2: Functional safety
fieldbuses – Additional specifications for CPF 2
IEC 61784-3-3, Industrial communication networks – Profiles – Part 3-3: Functional safety
fieldbuses – Additional specifications for CPF 3
IEC 61784-3-6, Industrial communication networks – Profiles – Part 3-6: Functional safety
fieldbuses – Additional specifications for CPF 6
IEC 61784-3-8 , Industrial communication networks – Profiles – Part 3-8: Functional safety
fieldbuses – Additional specifications for CPF 8
IEC 61784-3-12 , Industrial communication networks – Profiles – Part 3-12: Functional safety
fieldbuses – Additional specifications for CPF 12
IEC 61784-3-13 , Industrial communication networks – Profiles – Part 3-13: Functional safety
fieldbuses – Additional specifications for CPF 13
IEC 61784-3-14 , Industrial communication networks – Profiles – Part 3-14: Functional safety
fieldbuses – Additional specifications for CPF 14
IEC 61784-5 (all parts), Industrial communication networks – Profiles – Part 5: Installation of
fieldbuses – Installation profiles for CPF x
IEC 61918, Industrial communication networks – Installation of communication networks in
industrial premises
IEC 62280-1:2002, Railway applications – Communication, signalling and processing systems
– Part 1: Safety-related communication in closed transmission systems
—————————
To be published.
To be published.
61784-3  IEC:2010 – 13 –
IEC 62443 (all parts), Industrial communication networks – Network and system security
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
absolute time stamp
time stamp referenced to a global time which is common for a group of devices using a
fieldbus
[IEC 62280-2, modified]
3.1.1.2
availability
probability for an automated system that for a given period of time there are no unsatisfactory
system conditions such as loss of production
3.1.1.3
black channel
communication channel without available evidence of design or v
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