EN IEC 61784-3-19:2024

Industrial communication networks - Profiles - Part 3-19: Functional safety fieldbuses - Additional specifications for CPF 19

IEC 61784-3-19:2024 specifies a safety communication layer (services and protocol) based on IEC 61784‑1-19, IEC 61784-2-19 and the IEC 61158 series (Type 24 and Type 27). It identifies the principles for functional safety communications defined in IEC 61784‑3 that are relevant for this safety communication layer. This safety communication layer is intended for implementation in safety devices only. 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 document defines mechanisms for the transmission of safety-relevant messages among participants within a distributed network using fieldbus technology in accordance with the requirements of the IEC 61508 series for functional safety. These mechanisms can be used in various industrial applications such as process control, manufacturing automation and machinery. This document 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 document in a standard device is not sufficient to qualify it as a safety device.

Industrielle Kommunikationsnetze - Profile - Teil 3-19: Funktional sichere Übertragung bei Feldbussen - Zusätzliche Festlegungen für die Kommunikationsprofilfamilie 19

Réseaux de communication industriels – Profils – Partie 3-19: Bus de terrain de sécurité fonctionnelle – Spécifications supplémentaires pour CPF 19

IEC 61784-3-19:2024 spécifie une couche de communication de sécurité (services et protocole) fondée sur l'IEC 61784 1-19, l'IEC 61784-2-19 et la série IEC 61158 (Types 24 et 27). Elle identifie les principes qui s'appliquent aux communications de sécurité fonctionnelle définies dans l'IEC 61784 3, associées à cette couche de communication de sécurité qui est destinée à être mise en œuvre sur les appareils de sécurité uniquement. NOTE 1 Elle ne couvre pas les aspects relatifs à la sécurité électrique et à la sécurité intrinsèque. La sécurité électrique concerne les dangers comme les chocs électriques. La sécurité intrinsèque concerne les dangers associés aux atmosphères explosibles. Le présent document définit les mécanismes de transmission des messages relatifs à la sécurité entre les participants d'un réseau réparti, en utilisant la technologie de bus de terrain conformément aux exigences de la série IEC 61508 concernant la sécurité fonctionnelle. Ces mécanismes peuvent être utilisés dans différentes applications industrielles, par exemple la commande de processus, l'usinage automatique et les machines. Le présent document fournit des lignes directrices aux développeurs, ainsi qu'aux évaluateurs d'appareils et de systèmes conformes. NOTE 2 Le SIL ainsi revendiqué pour un système dépend de la mise en œuvre du profil de communication de sécurité fonctionnelle retenu au sein du système (la mise en œuvre d'un profil de communication de sécurité fonctionnelle conforme au présent document dans un appareil normal ne suffit pas à le qualifier d'appareil de sécurité).

Industrijska komunikacijska omrežja - Profili - 3-19. del: Funkcijska varnost procesnih vodil - Dodatne specifikacije za CPF 19 (IEC 61784-3-19:2024)

Ta del standarda IEC 61784-3 določa varnostni komunikacijski sloj (storitve in protokoli), ki temelji na standardih IEC 61784-1-19 in IEC 61784-2-19 ter skupini standardov IEC 61158 (tip 24 in tip 27). Določa načela za komunikacijsko funkcijsko varnost, opredeljeno v standardu IEC 61784-3, ki so pomembna za ta varnostni komunikacijski sloj. Ta varnostni komunikacijski sloj je namenjen za uporabo v varnostnih napravah.
OPOMBA 1: Standard ne zajema električne varnosti in intrinzičnih varnostnih vidikov. Električna varnost je povezana z nevarnostmi, kot je električni udar. Intrinzična varnost se navezuje na nevarnosti, ki so povezane s potencialno eksplozivnimi atmosferami.
Ta dokument določa mehanizme za prenos, ki jih je mogoče uporabiti pri prenosu z vidika varnosti pomembnih sporočil med udeleženci v porazdeljenem omrežju z uporabo tehnologije procesnih vodil v skladu z zahtevami skupine standardov IEC 61508 za funkcijsko varnost. Te mehanizme je mogoče uporabljati za različne industrijske namene, kot so vodenje procesov, proizvodna avtomatizacija in stroji.
Ta dokument zagotavlja smernice za razvijalce in ocenjevalce združljivih naprav in sistemov.
OPOMBA 2: Posledična stopnja varnostne celovitosti (SIL) sistema je odvisna od izvedbe izbranega komunikacijskega profila za funkcionalno varnost znotraj tega sistema. Izvedba komunikacijskega profila za funkcionalno varnost v standardni napravi v skladu s tem dokumentom ne zadostuje, da bi naprava izpolnjevala zahteve za varnostno napravo.

General Information

• Status: Published
• Publication Date: 21-Nov-2024
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.100.05 - Multilayer applications
• Technical Committee: CLC/TC 65X - Industrial-process measurement, control and automation
• Drafting Committee: CLC/TC 65X - Industrial-process measurement, control and automation
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 22-Nov-2024
• Due Date: 27-Dec-2024
• Completion Date: 22-Nov-2024
• Ref Project: SIST EN IEC 61784-3-19:2025 - Industrial communication networks - Profiles - Part 3-19: Functional safety fieldbuses - Additional specifications for CPF 19 (IEC 61784-3-19:2024)

Overview

EN IEC 61784-3-19:2024 specifies a safety communication layer for functional safety fieldbuses based on CPF 19 (Communication Profile Family 19). It defines services, protocol elements and implementation principles for transmitting safety‑relevant messages across distributed fieldbus networks (IEC 61158 Type 24 and Type 27). The standard aligns with the IEC 61508 functional safety requirements and is intended for implementation in safety devices only. It does not cover electrical safety or intrinsic safety aspects. EN IEC 61784-3-19:2024 also provides guidance for device developers and assessors to demonstrate compliance and to support system SIL (Safety Integrity Level) claims.

Key topics and technical requirements

• Safety communication layer (SCL): definition of services and message protocol elements for CPF 19 (often referenced as Mechatrolink Safety / FSCP 19).
• Service primitives and SPDU format: service names and primitives (for example S_CONNECT_START, S_SAFE_DATA, S_DISCONNECT, S_FAIL_SAFE, etc.) and the Safety Protocol Data Unit structure.
• Core safety mechanisms:
  • Sequence numbers and state numbers for freshness and ordering.
  • CRC calculation and redundant data / cross‑checking for data integrity.
  • Connection ID and connection management to isolate safety channels.
  • Time expectations and watchdogs (e.g., T_Watchdog, T_Response) to detect failures and timeouts.
• Safety FAL (Functional Application Layer) interaction: relationships with lower layers (DLL, PhL) and service protocol state machines for master/slave behavior.
• Parameters and management: definitions of device parameters (sequence numbers, connection keys, data lengths) and SCL management rules.
• Installation & system requirements: guidelines for indicators, switches, installation and response-time considerations relevant to safety functions.
• Compliance notes: the standard clarifies that SIL claims depend on the complete system implementation - implementing the profile in a standard device alone does not make it a certified safety device.

Applications

• Industrial process control
• Manufacturing automation and robotics
• Machinery safety systems
• Any distributed control application requiring certified transmission of safety-relevant data over fieldbus networks

Who should use this standard

• Safety device and fieldbus protocol developers
• Functional safety engineers and system integrators
• Certification bodies and assessors validating safety communications
• Automation OEMs implementing CPF 19 / Mechatrolink Safety solutions

Related standards

• IEC 61784-1-19, IEC 61784-2-19 (CPF 19 profile family)
• IEC 61158 series (Fieldbus specifications, Types 24 & 27)
• IEC 61508 series (Functional safety)
• IEC 61511, IEC 61784-3 and relevant EMC and installation standards

Keywords: EN IEC 61784-3-19:2024, CPF 19, functional safety fieldbuses, safety communication layer, Mechatrolink Safety, IEC 61508, safety protocol, fieldbus safety.

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2025
Industrijska komunikacijska omrežja - Profili - 3-19. del: Funkcijska varnost
procesnih vodil - Dodatne specifikacije za CPF 19 (IEC 61784-3-19:2024)
Industrial communication networks - Profiles - Part 3-19: Functional safety fieldbuses -
Additional specifications for CPF 19 (IEC 61784-3-19:2024)
Industrielle Kommunikationsnetze - Profile - Teil 3-19: Funktional sichere Übertragung
bei Feldbussen - Zusätzliche Festlegungen für die Kommunikationsprofilfamilie 19
Réseaux de communication industriels - Profils - Partie 3-19: Bus de terrain de sécurité
fonctionnelle - Spécifications supplémentaires pour CPF 19 (IEC 61784-3-19:2024)
Ta slovenski standard je istoveten z: EN IEC 61784-3-19:2024
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.100.05 Večslojne uporabniške Multilayer applications
rešitve
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61784-3-19

NORME EUROPÉENNE
EUROPÄISCHE NORM November 2024
ICS 25.040.40; 35.100.05
English Version
Industrial communication networks - Profiles - Part 3-19:
Functional safety fieldbuses - Additional specifications for CPF
(IEC 61784-3-19:2024)
Réseaux de communication industriels - Profils - Partie 3- Industrielle Kommunikationsnetze - Profile - Teil 3-19:
19: Bus de terrain de sécurité fonctionnelle - Spécifications Funktional sichere Übertragung bei Feldbussen -
supplémentaires pour CPF 19 Zusätzliche Festlegungen für die
(IEC 61784-3-19:2024) Kommunikationsprofilfamilie 19
(IEC 61784-3-19:2024)
This European Standard was approved by CENELEC on 2024-11-19. 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61784-3-19:2024 E

European foreword
The text of document 65C/1276/CDV, future edition 1 of IEC 61784-3-19, 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 IEC 61784-3-
19:2024.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2025-11-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2027-11-30
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61784-3-19:2024 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 standard indicated:
IEC 61000-1-2 NOTE Approved as EN 61000-1-2
IEC 61000-6-7 NOTE Approved as EN 61000-6-7
IEC 61010-2-201 NOTE Approved as EN IEC 61010-2-201
IEC 61131-6 NOTE Approved as EN 61131-6
IEC 61158-1 NOTE Approved as EN IEC 61158-1
IEC 61158-5 (series) NOTE Approved as EN 61158-5 (series)
IEC 61158-5-24 NOTE Approved as EN IEC 61158-5-24
IEC 61158-5-27 NOTE Approved as EN IEC 61158-5-27
IEC 61496 (series) NOTE Approved as EN IEC 61496 (series)
IEC 61508-1 NOTE Approved as EN 61508-1
IEC 61508-4:2010 NOTE Approved as EN 61508-4:2010 (not modified)
IEC 61508-5 NOTE Approved as EN 61508-5
IEC 61784-1 (series) NOTE Approved as EN IEC 61784-1 (series)
IEC 61784-2 (series) NOTE Approved as EN IEC 61784-2 (series)
IEC 61784-3 (series) NOTE Approved as EN IEC 61784-3 (series)
IEC 61784-5 (series) NOTE Approved as EN IEC 61784-5 (series)
IEC 61800-5-2 NOTE Approved as EN 61800-5-2
IEC 61918 NOTE Approved as EN IEC 61918
IEC 62443 (series) NOTE Approved as EN IEC 62443 (series)
ISO 10218-1:2011 NOTE Approved as EN ISO 10218-1:2011 (not modified)
ISO 13849 (series) NOTE Approved as EN ISO 13849 (series)
ISO 13849-1:2023 NOTE Approved as EN ISO 13849-1:2023 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 1 Where 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.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 61131-2 - Industrial-process measurement and EN 61131-2 -
control - Programmable controllers - Part 2:
Equipment requirements and tests
IEC 61158 series Industrial communication networks - EN IEC 61158 series
Fieldbus specifications
IEC 61158-6-24 - Industrial communication networks - EN IEC 61158-6-24 -
Fieldbus specifications - Part 6-24:
Application layer protocol specification -
Type 24 elements
IEC 61158-6-27 - Industrial communication networks - EN IEC 61158-6-27 -
Fieldbus Specifications Part 6-27:
Application layer protocol specification -
Type 27 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
IEC 61326-3-2 - Electrical equipment for measurement, EN IEC 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 61784-1-19 2023 Industrial networks - Profiles - Part 1-19: EN IEC 61784-1-19 2023
Fieldbus profiles - Communication Profile
Family 19
IEC 61784-2-19 2023 Industrial networks - Profiles - Part 2-19: EN IEC 61784-2-19 2023
Additional real-time fieldbus profiles based
on ISO/IEC/IEEE 8802-3 - CPF 19
IEC 61784-3 - Industrial communication networks - EN IEC 61784-3 -
Profiles - Part 3: Functional safety
fieldbuses - General rules and profile
definitions
IEC 61784-5-19 - Industrial networks - Profiles - Part 5-19: EN IEC 61784-5-19 -
Installation of fieldbuses - Installation
profiles for CPF 19
IEC 62061 - Safety of machinery - Functional safety of EN IEC 62061 -
safety-related control systems

IEC 61784-3-19 ®
Edition 1.0 2024-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Profiles –

Part 3-19: Functional safety fieldbuses – Additional specifications for CPF 19

Réseaux de communication industriels – Profils –

Partie 3-19: Bus de terrain de sécurité fonctionnelle – Spécifications

supplémentaires pour CPF 19
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40, 35.100.05 ISBN 978-2-8322-9802-2

– 2 – IEC 61784-3-19:2024 © IEC 2024
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
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 19: Additional terms and definitions . 15
3.2 Symbols and abbreviated terms . 15
3.2.1 Common symbols and abbreviated terms . 15
3.2.2 CPF 19: Additional symbols and abbreviated terms . 16
3.3 Conventions . 16
4 Overview of FSCP 19 (MECHATROLINK Safety) . 16
5 General . 17
5.1 External documents providing specifications for the profile . 17
5.2 Safety functional requirements . 17
5.3 Safety measures . 17
5.3.1 General . 17
5.3.2 Sequence number. 18
5.3.3 Time expectation . 19
5.3.4 Connection ID . 21
5.3.5 CRC calculation . 21
5.3.6 Redundancy with cross checking . 22
5.4 Safety communication layer structure . 25
5.5 Relationships with FAL (and DLL, PhL) . 26
5.5.1 General . 26
5.5.2 Data types . 26
6 Safety communication layer services . 26
6.1 Service description . 26
6.1.1 S_CONNECT_START . 26
6.1.2 S_CONNECT_CONF . 28
6.1.3 S_PRM_SET . 31
6.1.4 S_PRM_APPLY . 33
6.1.5 S_SAFE_DATA . 34
6.1.6 S_DISCONNECT . 35
6.1.7 S_FAIL_SAFE . 36
6.1.8 S_NOP . 37
7 SCL protocol . 38
7.1 SPDU format . 38
7.1.1 SPDU structure . 38
7.1.2 Connection ID . 39
7.1.3 Sequence number. 39
7.1.4 Command . 39
7.1.5 State number . 40
7.1.6 CRC . 40
7.1.7 Redundant data . 40

IEC 61784-3-19:2024 © IEC 2024 – 3 –
7.2 Safety FAL service protocol machine . 40
7.2.1 State transition of safety master . 40
7.2.2 State transition of safety slave . 47
7.3 Behaviour description . 53
7.3.1 Connection establishment . 53
7.3.2 Safety data sending/receiving sequence . 60
7.3.3 Disconnect safety channel . 64
8 SCL management . 65
8.1 Parameter definitions . 65
8.1.1 General . 65
8.1.2 T_Watchdog . 65
8.1.3 T_Response . 65
8.1.4 Master_Connection_Key . 66
8.1.5 Slave_Connection_Key . 66
8.1.6 Connection_Id . 66
8.1.7 Master_Sequence_Number . 66
8.1.8 Extended_Master_Sequence_Number . 66
8.1.9 Slave_Sequence_Number. 66
8.1.10 Extended_Slave_Sequence_Number . 66
8.1.11 Node_Address . 66
8.1.12 Device_Info (structure) . 67
8.1.13 Output_Data_Length . 67
8.1.14 Input_Data_Length . 67
8.1.15 Output_User_Data_Length . 67
8.1.16 Input_User_Data_Length . 67
8.1.17 Stop_Safety_Loop . 67
8.1.18 Stop_Safety_Loop_Oth . 68
9 System requirements . 69
9.1 Indicators and switches . 69
9.1.1 General . 69
9.1.2 Safety connection LED . 70
9.2 Installation guidelines . 70
9.3 Safety function response time . 70
9.3.1 System response time . 70
9.3.2 FSCP 19 response time . 71
9.4 Duration of demands . 72
9.5 Constraints for calculation of system characteristics . 72
9.5.1 Number of stations . 72
9.5.2 Probability considerations . 72
9.6 Maintenance . 73
9.7 Safety manual . 73
10 Assessment . 73
Bibliography . 74

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 – Basic FSCP 19 system . 17
Figure 4 – Incrementing procedure of sequence number . 19

– 4 – IEC 61784-3-19:2024 © IEC 2024
Figure 5 – Time expectation with watchdog timer . 20
Figure 6 – Synchronization of transmission timing. 20
Figure 7 – Time expectation with response timer . 21
Figure 8 – Redundant data generation processing . 23
Figure 9 – Redundant data verification process . 25
Figure 10 – SCL structure . 26
Figure 11 – Safety PDU format . 38
Figure 12 – Safety master SCL – state transition diagram . 40
Figure 13 – Safety master safety connection − state transition diagram . 42
Figure 14 – Safety slave SCL − state transition diagram . 48
Figure 15 – Safety slave safety connection − state transition diagram . 49
Figure 16 – Node address and device information processing flow at start-up . 56
Figure 17 – S_CONNECT_START command reception processing flow . 56
Figure 18 – S_CONNECT_CONF command reception processing flow . 57
Figure 19 – Sequence example 1 from connection establishment to safety data
transmission/reception . 58
Figure 20 – Sequence example 2 from connection establishment to safety data

transmission/reception . 59
Figure 21 – S_SAFE_DATA command sequence . 60
Figure 22 – Loss of S_SAFE_DATA command from safety master . 61
Figure 23 – Delay of S_SAFE_DATA command from safety master . 61
Figure 24 – Loss of S_SAFE_DATA command from safety slave . 62
Figure 25 – Delay of S_SAFE_DATA command from safety slave . 62
Figure 26 – Insertion of message to safety slave . 63
Figure 27 – Insertion of message to safety master . 64
Figure 28 – Elements of safety function . 71
Figure 29 – Safety function of FSCP 19 system . 71
Figure 30 – Residual error rate . 73

Table 1 – Communication errors and safety measures . 18
Table 2 – Sequence number list . 18
Table 3 – CRC seed values . 22
Table 4 – S_CONNECT_START command data. 27
Table 5 – S_CONNECT_START command SPDU (1st SPDU) . 27
Table 6 – S_CONNECT_START command SPDU (2nd SPDU) . 28
Table 7 – S_CONNECT_CONF command data . 29
Table 8 – S_CONNECT_CONF command SPDU (1st SPDU) . 29
Table 9 – S_CONNECT_CONF command SPDU (2nd SPDU) . 30
Table 10 – S_CONNECT_CONF command SPDU (3rd SPDU) . 30
Table 11 – S_PRM_SET command data . 31
Table 12 – S_PRM_SET command SPDU (1st SPDU) . 32
Table 13 – S_PRM_SET command SPDU (2nd SPDU) . 32
Table 14 – S_PRM_SET command SPDU (3rd SPDU) . 33
Table 15 – S_PRM_APPLY command data . 33

IEC 61784-3-19:2024 © IEC 2024 – 5 –
Table 16 – S_PRM_APPLY command SPDU . 34
Table 17 – S_SAFE_DATA command SPDU . 34
Table 18 – S_DISCONNECT command SPDU . 35
Table 19 – Factor in S_DISCONNECT command . 36
Table 20 – S_FAIL_SAFE command SPDU . 37
Table 21 – S_NOP command SPDU . 37
Table 22 – List of commands . 39
Table 23 – Safety master SCL – state description . 40
Table 24 – Safety master SCL − state transition matrix . 41
Table 25 – Safety master safety connection − state description . 43
Table 26 – Safety master safety connection − state transition matrix . 43
Table 27 – Safety slave SCL − state description . 48
Table 28 – Safety slave SCL – state transition matrix . 48
Table 29 – Safety slave safety connection − state description . 49
Table 30 – Safety slave safety connection − state transition matrix . 50
Table 31 – Safety salve node and device variables . 55
Table 32 – List of parameter variables . 65
Table 33 – Specification of stop safety loop setting . 68
Table 34 – Specification of stop safety loop other setting . 69
Table 35 – LED specifications . 70
Table 36 – Safety connection LED specification . 70
Table 37 – Residual error rate . 72

– 6 – IEC 61784-3-19:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES –
Part 3-19: Functional safety fieldbuses –
Additional specifications for CPF 19

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.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of a patent.
IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect
thereof. As of the date of publication of this document, IEC had received notice of a patent, which may be required
to implement this document. However, implementers are cautioned that this may not represent the latest
information, which may be obtained from the patent database available at https://patents.iec.ch. IEC shall not be
held responsible for identifying any or all such patent rights.
IEC 61784-3-19 has been prepared by subcommittee 65C: Industrial networks, of IEC technical
committee 65: Industrial-process measurement, control and automation. It is an International
Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
65C/1276/CDV 65C/1298/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
IEC 61784-3-19:2024 © IEC 2024 – 7 –
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
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 document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
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 – IEC 61784-3-19:2024 © IEC 2024
INTRODUCTION
The IEC 61158 fieldbus standard series together with its companion standards series
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 and safety-related applications.
The IEC 61784-3 series explains the relevant principles for functional safety communications
with reference to the IEC 61508 series and specifies several safety communication layers
(profiles and corresponding protocols) based on the communication profiles and protocol layers
of the IEC 61784-1, IEC 61784-2 and IEC 61158 series. It does not cover electrical safety and
intrinsic safety aspects. It also does not cover security aspects, nor does it provide any
requirements for security.
Figure 1 shows the relationships between the IEC 61784-3 series and relevant safety and
fieldbus standards in a machinery environment.

NOTE IEC 62061 specifies the relationship between PL (Category) and SIL.
Figure 1 – Relationships of IEC 61784-3 with other standards (machinery)
Figure 2 shows the relationships between the IEC 61784-3 series and relevant safety and
fieldbus standards in a process environment.

IEC 61784-3-19:2024 © IEC 2024 – 9 –

a
For specified electromagnetic environments; otherwise IEC 61326-3-1 or IEC 61000-6-7.
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 the 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 the IEC 61784-3 series 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.
The IEC 61784-3 series describes:
• basic principles for implementing the requirements of the 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 the
IEC 61784-1 and IEC 61784-2 series, including safety layer extensions to the
communication service and protocols sections of the IEC 61158 series.

– 10 – IEC 61784-3-19:2024 © IEC 2024
INDUSTRIAL COMMUNICATION NETWORKS –
PROFILES –
Part 3-19: Functional safety fieldbuses –
Additional specifications for CPF 19

1 Scope
This part of IEC 61784-3 specifies a safety communication layer (services and protocol) based
on IEC 61784-1-19, IEC 61784-2-19 and the IEC 61158 series (Type 24 and Type 27). It
identifies the principles for functional safety communications defined in IEC 61784-3 that are
relevant for this safety communication layer. This safety communication layer is intended for
implementation in safety devices only.
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 document defines mechanisms for the transmission of safety-relevant messages among
participants within a distributed network using fieldbus technology in accordance with the
requirements of the IEC 61508 series for functional safety. These mechanisms can be used in
various industrial applications such as process control, manufacturing automation and
machinery.
This document 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 document in a standard device is not sufficient to qualify it as a safety device.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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, Industrial-process measurement and control – Programmable controllers – Part 2:
Equipment requirements and tests
IEC 61158 (all parts), Industrial communication networks – Fieldbus specifications
IEC 61158-6-24, Industrial communication networks – Fieldbus specifications – Part 6-24:
Application layer protocol specification – Type 24 elements
IEC 61158-6-27, Industrial communication networks – Fieldbus specifications – Part 6-27:
Application layer protocol specification – Type 27 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
___________
In the following pages of this document, "IEC 61508" will be used for "the IEC 61508 series".

IEC 61784-3-19:2024 © IEC 2024 – 11 –
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 61784-1-19:2023, Industrial networks – Profiles – Part 1-19: Fieldbus profiles –
Communication Profile Family 19
IEC 61784-2-19:2023, Industrial networks – Profiles – Part 2-19: Additional real-time fieldbus
profiles based on ISO/IEC/IEEE 8802-3 – CPF 19
IEC 61784-3, Industrial communication networks − Profiles − Part 3: Functional safety
fieldbuses − General rules and profile definitions
IEC 61784-5-19, Industrial networks – Profiles – Part 5: Installation of fieldbuses – Installation
profiles for CPF 19
IEC 62061, Safety of machinery – Functional safety of safety-related control systems
3 Terms, definitions, symbols, abbreviated terms and conventions
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61784-3 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
NOTE Italics are used in the definitions to highlight terms which are themselves defined in 3.1.
3.1.1 Common terms and definitions
NOTE These common terms and definitions are inherited from IEC 61784-3:2021.
3.1.1.1
communication channel
logical connection between two end-points within a communication system
3.1.1.2
communication system
arrangement of hardware, software and propagation media to allow the transfer of messages
(ISO/IEC 7498-1 application layer) from one application to another
3.1.1.3
connection
logical binding between two application objects within the same or different devices

– 12 – IEC 61784-3-19:2024 © IEC 2024
3.1.1.4
CRC
Cyclic Redundancy Check
redundant data derived from, and stored or transmitted together with, a block of data
in order to detect data corruption
3.1.1.5
CRC
Cyclic Redundancy Check
procedure used to calculate the redundant data
Note 1 to entry: Terms "CRC code" and "CRC signature", and labels such as CRC1, CRC2, can also be used in this
document to refer to the redundant data.
3.1.1.6
error
discrepancy between a computed, observed or measured value or condition and the true,
specified or theoretically correct value or condition
Note 1 to entry: Errors can be due to design mistakes within hardware/software and/or corrupted information due
to electromagnetic interference and/or other effects.
Note 2 to entry: Errors do not necessarily result in a failure or a fault.
[SOURCE: IEC 61508-4:2010, 3.6.11, modified – Notes to entry have been added.]
3.1.1.7
failure
termination of the ability of a functional unit to provide a required function or operation of a
functional unit in any way other than as required
Note 1 to entry: Failure can be due to an error (for example, problem with hardware/software design or message
disruption).
[SOURCE: IEC 61508-4:2010, 3.6.4, modified – Notes and figures have been replaced.]
3.1.1.8
fault
abnormal condition that
...