Industrial communication networks - Profiles - Part 3: Functional safety fieldbuses - General rules and profile definitions

IEC 61784-3:2021 explains some common principles that can be used in the transmission of safety-relevant messages among participants within a distributed network which use fieldbus technology in accordance with the requirements of IEC 61508 (all parts) for functional safety. These principles are based on the black channel approach. They can be used in various industrial applications such as process control, manufacturing automation and machinery.

Réseaux de communication industriels - Profils - Partie 3: Bus de terrain de sécurité fonctionnelle - Règles générales et définitions de profils

L'IEC 61784-3:2021 définit des principes communs qui peuvent être appliqués pour la transmission des messages relatifs à la sécurité entre les participants d'un réseau réparti, à l'aide de la technologie de bus de terrain conformément aux exigences de l'IEC 61508 (toutes les parties) sur la sécurité fonctionnelle. Ces principes s'appuient sur le principe de canal noir. Ils peuvent être utilisés dans différentes applications industrielles, par exemple la commande de processus, l'usinage automatique et les machines.

General Information

Status
Published
Publication Date
15-Feb-2021
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
16-Feb-2021
Ref Project

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IEC 61784-3
Edition 4.0 2021-02
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
IEC 61784-3:2021-02(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61784-3
Edition 4.0 2021-02
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 978-2-8322-9268-6

Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61784-3:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 7

0 Introduction ..................................................................................................................... 9

0.1 General ................................................................................................................... 9

0.2 Use of extended assessment methods in Edition 4 ................................................ 11

0.3 Patent declaration ................................................................................................. 11

1 Scope ............................................................................................................................ 12

2 Normative references .................................................................................................... 12

3 Terms, definitions, symbols, abbreviated terms and conventions ................................... 14

3.1 Terms and definitions ............................................................................................ 14

3.2 Symbols and abbreviated terms ............................................................................ 21

3.2.1 Abbreviated terms ......................................................................................... 21

3.2.2 Symbols ........................................................................................................ 22

4 Conformance ................................................................................................................. 22

5 Basics of safety-related fieldbus systems ...................................................................... 23

5.1 Safety function decomposition .............................................................................. 23

5.2 Communication system ......................................................................................... 23

5.2.1 General ......................................................................................................... 23

5.2.2 IEC 61158 fieldbuses ..................................................................................... 24

5.2.3 Communication channel types ....................................................................... 24

5.2.4 Safety function response time ........................................................................ 25

5.3 Communication errors ........................................................................................... 25

5.3.1 General ......................................................................................................... 25

5.3.2 Corruption ..................................................................................................... 25

5.3.3 Unintended repetition .................................................................................... 26

5.3.4 Incorrect sequence ........................................................................................ 26

5.3.5 Loss .............................................................................................................. 26

5.3.6 Unacceptable delay ....................................................................................... 26

5.3.7 Insertion ........................................................................................................ 26

5.3.8 Masquerade................................................................................................... 26

5.3.9 Addressing .................................................................................................... 26

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 ........................................................................................... 27

5.4.5 Connection authentication ............................................................................. 27

5.4.6 Feedback message ........................................................................................ 27

5.4.7 Data integrity assurance ................................................................................ 27

5.4.8 Redundancy with cross checking ................................................................... 28

5.4.9 Different data integrity assurance systems ..................................................... 28

5.5 Typical relationships between errors and safety measures .................................... 28

5.6 Communication phases ......................................................................................... 29

5.7 FSCP implementation aspects .............................................................................. 30

5.8 Models for estimation of the total residual error rate ............................................. 30

5.8.1 Applicability ................................................................................................... 30

5.8.2 General models for black channel communications ........................................ 31

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IEC 61784-3:2021 © IEC 2021 – 3 –

5.8.3 Identification of generic safety properties ....................................................... 31

5.8.4 Assumptions for residual error rate calculations ............................................. 32

5.8.5 Residual error rates ....................................................................................... 33

5.8.6 Data integrity ................................................................................................. 35

5.8.7 Authenticity.................................................................................................... 36

5.8.8 Timeliness ..................................................................................................... 38

5.8.9 Masquerade................................................................................................... 41

5.8.10 Calculation of the total residual error rates .................................................... 41

5.8.11 Total residual error rate and SIL .................................................................... 43

5.8.12 Configuration and parameterization for an FSCP ........................................... 43

5.9 Relationship between functional safety and security ............................................. 45

5.10 Boundary conditions and constraints ..................................................................... 45

5.10.1 Electrical safety ............................................................................................. 45

5.10.2 Electromagnetic compatibility (EMC) ............................................................. 46

5.11 Installation guidelines ........................................................................................... 46

5.12 Safety manual ....................................................................................................... 46

5.13 Safety policy ......................................................................................................... 46

6 Communication Profile Family 1 (FOUNDATION™ Fieldbus) – Profiles for functional

safety ............................................................................................................................ 47

7 Communication Profile Family 2 (CIP™) and Family 16 (SERCOS®) – Profiles for

functional safety ............................................................................................................ 47

8 Communication Profile Family 3 (PROFIBUS™, PROFINET™) – Profiles for

functional safety ............................................................................................................ 48

9 Communication Profile Family 6 (INTERBUS®) – Profiles for functional safety .............. 48

10 Communication Profile Family 8 (CC-Link™) – Profiles for functional safety .................. 49

10.1 Functional Safety Communication Profile 8/1 ........................................................ 49

10.2 Functional Safety Communication Profile 8/2 ........................................................ 49

11 Communication Profile Family 12 (EtherCAT™) – Profiles for functional safety.............. 49

12 Communication Profile Family 13 (Ethernet POWERLINK™) – Profiles for

functional safety ............................................................................................................ 50

13 Communication Profile Family 14 (EPA®) – Profiles for functional safety ....................... 50

14 Communication Profile Family 17 (RAPIEnet™) – Profiles for functional safety.............. 50

15 Communication Profile Family 18 (SafetyNET p™ Fieldbus) – Profiles for

functional safety ............................................................................................................ 51

Annex A (informative) Example functional safety communication models ............................. 52

A.1 General ................................................................................................................. 52

A.2 Model A (single message, channel and FAL, redundant SCLs) .............................. 52

A.3 Model B (full redundancy) ..................................................................................... 52

A.4 Model C (redundant messages, FALs and SCLs, single channel) .......................... 53

A.5 Model D (redundant messages and SCLs, single channel and FAL) ...................... 53

Annex B (normative) Safety communication channel model using CRC-based error

checking ............................................................................................................................... 55

B.1 Overview............................................................................................................... 55

B.2 Channel model for calculations ............................................................................. 55

B.3 Bit error probability Pe .......................................................................................... 56

B.4 Cyclic redundancy checking .................................................................................. 57

B.4.1 General ......................................................................................................... 57

B.4.2 Requirements for methods to calculate R ............................................... 57

CRC

Annex C (informative) Structure of technology-specific parts................................................ 59

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– 4 – IEC 61784-3:2021 © IEC 2021

Annex D (informative) Assessment guideline ....................................................................... 62

D.1 Overview............................................................................................................... 62

D.2 Channel types ....................................................................................................... 62

D.2.1 General ......................................................................................................... 62

D.2.2 Black channel ................................................................................................ 62

D.2.3 White channel ................................................................................................ 62

D.3 Data integrity considerations for white channel approaches .................................. 63

D.3.1 General ......................................................................................................... 63

D.3.2 Models B and C ............................................................................................. 63

D.3.3 Models A and D ............................................................................................. 64

D.4 Verification of safety measures ............................................................................. 64

D.4.1 General ......................................................................................................... 64

D.4.2 Implementation .............................................................................................. 65

D.4.3 Default safety action ...................................................................................... 65

D.4.4 Safe state ...................................................................................................... 65

D.4.5 Transmission errors ....................................................................................... 65

D.4.6 Safety reaction and response times ............................................................... 65

D.4.7 Combination of measures .............................................................................. 65

D.4.8 Absence of interference ................................................................................. 66

D.4.9 Additional fault causes (white channel) .......................................................... 66

D.4.10 Reference test beds and operational conditions ............................................. 66

D.4.11 Conformance tester ....................................................................................... 66

Annex E (informative) Examples of implicit vs. explicit FSCP safety measures..................... 67

E.1 General ................................................................................................................. 67

E.2 Example fieldbus message with safety PDUs ........................................................ 67

E.3 Model with completely explicit safety measures .................................................... 67

E.4 Model with explicit A-code and implicit T-code safety measures ............................ 68

E.5 Model with explicit T-code and implicit A-code safety measures ............................ 68

E.6 Model with split explicit and implicit safety measures ............................................ 69

E.7 Model with completely implicit safety measures .................................................... 70

E.8 Addition to Annex B – impact of implicit codes on properness ............................... 70

Annex F (informative) Legacy models for estimation of the total residual error rate .............. 71

F.1 General ................................................................................................................. 71

F.2 Calculation of the residual error rate ..................................................................... 71

F.3 Total residual error rate and SIL ........................................................................... 73

Annex G (informative) Implicit data safety mechanisms for IEC 61784-3 functional

safety communication profiles (FSCPs) ................................................................................. 74

G.1 Overview............................................................................................................... 74

G.2 Basic principles ..................................................................................................... 74

G.3 Problem statement: constant values for implicit data ............................................. 75

G.4 RP for FSCPs with random, uniformly distributed err ...................................... 78

impl

G.4.1 General ......................................................................................................... 78

G.4.2 Uniform distribution within the interval [0;2 -1], i ≥ r ....................................... 79

G.4.3 Uniform distribution in the interval [1;2 -1], i = r ............................................. 81

G.5 General case ........................................................................................................ 83

G.6 Calculation of P ................................................................................................. 83

Annex H (informative) Residual error probability for example CRC codes (tables for

verification of calculation methods) ....................................................................................... 85

H.1 Overview............................................................................................................... 85

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IEC 61784-3:2021 © IEC 2021 – 5 –

H.2 Example of a 32-bit CRC....................................................................................... 85

H.3 Example of a 16-bit CRC....................................................................................... 90

H.4 Conclusion ............................................................................................................ 94

Bibliography .......................................................................................................................... 96

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 – Transitions from Ed. 2 to Ed. 4 and future Ed. 5 assessment methods ................. 11

Figure 4 – Safety communication as a part of a safety function ............................................. 23

Figure 5 – Example model of a functional safety communication system ............................... 24

Figure 6 – Example of safety function response time components ......................................... 25

Figure 7 – Conceptual FSCP protocol model ......................................................................... 30

Figure 8 – FSCP implementation aspects.............................................................................. 30

Figure 9 – Black channel from an FSCP perspective ............................................................. 31

Figure 10 – Model for authentication considerations ............................................................. 36

Figure 11 – Fieldbus and internal address errors .................................................................. 37

Figure 12 – Example of slowly increasing message latency .................................................. 39

Figure 13 – Example of an active network element failure ..................................................... 40

Figure 14 – Example application 1 (m = 4) ............................................................................ 42

Figure 15 – Example application 2 (m = 2) ............................................................................ 42

Figure 16 – Example of configuration and parameterization procedures for FSCP ................. 44

Figure A.1 – Model A ............................................................................................................ 52

Figure A.2 – Model B ............................................................................................................ 53

Figure A.3 – Model C ............................................................................................................ 53

Figure A.4 – Model D ............................................................................................................ 54

Figure B.1 – Binary symmetric channel (BSC) ....................................................................... 55

Figure B.2 – Block codes for error detection ......................................................................... 56

Figure B.3 – Example of a block with a message part and a CRC signature .......................... 57

Figure B.4 – Proper and improper CRC polynomials ............................................................. 58

Figure D.1 – Basic Markov model ......................................................................................... 64

Figure E.1 – Example safety PDUs embedded in a fieldbus message ................................... 67

Figure E.2 – Model with completely explicit safety measures ................................................ 67

Figure E.3 – Model with explicit A-code and implicit T-code safety measures ........................ 68

Figure E.4 – Model with explicit T-code and implicit A-code safety measures ........................ 69

Figure E.5 – Model with split explicit and implicit safety measures ........................................ 69

Figure E.6 – Model with completely implicit safety measures ................................................ 70

Figure F.1 – Example application 1 (m = 4) ........................................................................... 72

Figure F.2 – Example application 2 (m = 2) ........................................................................... 73

Figure G.1 – FSCP with implicit transmission of authenticity and/or timeliness codes ........... 75

Figure G.2 – Example of an incorrect transmission with multiple error causes ....................... 76

Figure G.3 – Impact of errors in implicit data on the residual error probability ....................... 77

Figure H.1 – Residual error probabilities (example of a 32-bit CRC – result 1) ...................... 87

Figure H.2 – Residual error probabilities (example of a 32-bit CRC – result 2) ...................... 87

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– 6 – IEC 61784-3:2021 © IEC 2021

Figure H.3 – Residual error probabilities (example of a 32-bit CRC – result 3) ...................... 88

Figure H.4 – Residual error probabilities (example of a 32-bit CRC – result 4) ...................... 88

Figure H.5 – Residual error probabilities (example of a 32-bit CRC – result 5) ...................... 89

Figure H.6 – Residual error probabilities (example of a 32-bit CRC – result 6) ...................... 89

Figure H.7 – Residual error probabilities (example of a 16-bit CRC – result 1) ...................... 92

Figure H.8 – Residual error probabilities (example of a 16-bit CRC – result 2) ...................... 92

Figure H.9 – Residual error probabilities (example of a 16-bit CRC – result 3) ...................... 93

Figure H.10 – Residual error probabilities (example of a 16-bit CRC – result 4) .................... 93

Figure H.11 – Residual error probabilities (example of a 16-bit CRC – result 5) .................... 94

Figure H.12 – Example 1 of improper polynomial .................................................................. 94

Figure H.13 – Example 2 of improper polynomial .................................................................. 95

Table 1 – Overview of the effectiveness of the various measures on the possible errors ....... 29

Table 2 – Typical relationship of residual error rate to SIL .................................................... 43

Table 3 – Typical relationship of residual error on demand to SIL ......................................... 43

Table 4 – Overview of profile identifier usable for FSCP 6/7 .................................................. 48

Table B.1 – Example dependency d and block bit length n .............................................. 56

min

Table C.1 – Common subclause structure for technology-specific parts ................................ 59

Table F.1 – Definition of items used for calculation of the residual error rates .........

...

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