AS/NZS 62061:2025
Safety of machinery – Functional safety of safety-related control systems
Standard specifies requirements and make recommendations for the design, integration and validation of safety-related control systems (SCS) for machines. It is applicable to control systems used, either singly or in combination, to carry out safety functions on machines that are not portable by hand while working, including a group of machines working together in a coordinated manner.
This document is a machinery sector specific standard within the framework of AS 61508 (all parts).
The design of complex programmable electronic subsystems or subsystem elements is not within the scope of this document. This is in the scope of AS 61508 or standards linked to it.
This document is an adoption with national modifications, and has been reproduced from IEC 62061:2021, Safety of machinery – Functional safety of safety-related control systems, and its amendment, which has been added at the end of the source text.
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AS/NZS 62061:2025 Safety of machinery - Functional safety of safety-related control systems
Preface
FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms, definitions and abbreviations
3.1 Alphabetical list of definitions
3.2 Terms and definitions
3.3 Abbreviations
4 Design process of an SCS and management of functional safety
4.1 Objective
4.2 Design process
4.3 Management of functional safety using a functional safety plan
4.4 Configuration management
4.5 Modification
5 Specification of a safety function
5.1 Objective
5.2 Safety requirements specification (SRS)
5.2.1 General
5.2.2 Information to be available
5.2.3 Functional requirements specification
5.2.4 Estimation of demand mode of operation
5.2.5 Safety integrity requirements specification
6 Design of an SCS
6.1 General
6.2 Subsystem architecture based on top down decomposition
6.3 Basic methodology – Use of subsystem
6.3.1 General
6.3.2 SCS decomposition
6.3.3 Sub-function allocation
6.3.4 Use of a pre-designed subsystem
6.4 Determination of safety integrity of the SCS
6.4.1 General
6.4.2 PFH
6.5 Requirements for systematic safety integrity of the SCS
6.5.1 Requirements for the avoidance of systematic hardware failures
6.5.2 Requirements for the control of systematic faults
6.6 Electromagnetic immunity
6.7 Software based manual parameterization
6.7.1 General
6.7.2 Influences on safety-related parameters
6.7.3 Requirements for software based manual parameterization
6.7.4 Verification of the parameterization tool
6.7.5 Performance of software based manual parameterization
6.8 Security aspects
6.9 Aspects of periodic testing
7 Design and development of a subsystem
7.1 General
7.2 Subsystem architecture design
7.3 Requirements for the selection and design of subsystem and subsystem elements
7.3.1 General
7.3.2 Systematic integrity
7.3.3 Fault consideration and fault exclusion
7.3.4 Failure rate of subsystem element
7.4 Architectural constraints of a subsystem
7.4.1 General
7.4.2 Estimation of safe failure fraction (SFF)
7.4.3 Behaviour (of the SCS) on detection of a fault in a subsystem
7.4.4 Realization of diagnostic functions
7.5 Subsystem design architectures
7.5.1 General
7.5.2 Basic subsystem architectures
7.5.3 Basic requirements
7.6 PFH of subsystems
7.6.1 General
7.6.2 Methods to estimate the PFH of a subsystem
7.6.3 Simplified approach to estimation of contribution of common cause failure (CCF)
8 Software
8.1 General
8.2 Definition of software levels
8.3 Software – Level 1
8.3.1 Software safety lifecycle – SW level 1
8.3.2 Software design – SW level 1
8.3.3 Module design – SW level 1
8.3.4 Coding – SW level 1
8.3.5 Module test – SW level 1
8.3.6 Software testing – SW level 1
8.3.7 Documentation – SW level 1
8.3.8 Configuration and modification management process – SW level 1
8.4 Software level 2
8.4.1 Software safety lifecycle – SW level 2
8.4.2 Software design – SW level 2
8.4.3 Software system design – SW level 2
8.4.4 Module design – SW level 2
8.4.5 Coding – SW level 2
8.4.6 Module test – SW level 2
8.4.7 Software integration testing SW level 2
8.4.8 Software testing SW level 2
8.4.9 Documentation – SW level 2
8.4.10 Configuration and modification management process – SW level 2
9 Validation
9.1 Validation principles
9.1.1 Validation plan
9.1.2 Use of generic fault lists
9.1.3 Specific fault lists
9.1.4 Information for validation
9.1.5 Validation record
9.2 Analysis as part of validation
9.2.1 General
9.2.2 Analysis techniques
9.2.3 Verification of safety requirements specification (SRS)
9.3 Testing as part of validation
9.3.1 General
9.3.2 Measurement accuracy
9.3.3 More stringent requirements
9.3.4 Test samples
9.4 Validation of the safety function
9.4.1 General
9.4.2 Analysis and testing
9.5 Validation of the safety integrity of the SCS
9.5.1 General
9.5.2 Validation of subsystem(s)
9.5.3 Validation of measures against systematic failures
9.5.4 Validation of safety-related software
9.5.5 Validation of combination of subsystems
10 Documentation
10.1 General
10.2 Technical documentation
10.3 Information for use of the SCS
10.3.1 General
10.3.2 Information for use given by the manufacturer of subsystems
10.3.3 Information for use given by the SCS integrator
Annex A (informative) Determination of required safety integrity
Annex B (informative) Example of SCS design methodology
Annex C (informative) Examples of MTTFD values for single components
Annex D (informative) Examples for diagnostic coverage (DC)
Annex E (informative) Methodology for the estimation of susceptibility to common cause failures (CCF)
Annex F (informative) Guideline for software level 1
Annex G (informative) Examples of safety functions
Annex H (informative) Simplified approaches to evaluate the PFH value of a subsystem
Annex I (informative) The functional safety plan and design activities
Annex J (informative) Independence for reviews and testing/verification/validation activities
Bibliography
Amendment 1
Figure 1 — Scope of this document
Figure 2 — Integration within the risk reduction process of ISO 12100 (extract)
Figure 3 — Iterative process for design of the safety-related control system
Figure 4 — Example of a combination of subsystems as one SCS
Figure 5 — By activating a low demand safety function at least once per year it can be assumed to be high demand
Figure 6 — Examples of typical decomposition of a safety function into sub-functions and its allocation to subsystems
Figure 7 — Example of safety integrity of a safety function based on allocated subsystems as one SCS
Figure 8 — Subsystem A logical representation
Figure 9 — Subsystem B logical representation
Figure 10 — Subsystem C logical representation
Figure 11 — Subsystem D logical representation
Figure 12 — V-model for SW level 1
Figure 13 — V-model for software modules customized by the designer for SW level 1
Figure 14 — V-model of software safety lifecycle for SW level 2
Figure 15 — Overview of the validation process
Figure A.1 — Parameters used in risk estimation
Figure A.2 — Example proforma for SIL assignment process
Figure B.1 — Decomposition of the safety function
Figure B.2 — Overview of design of the subsystems of the SCS
Figure F.1 — Plant sketch
Figure F.2 — Principal module architecture design
Figure F.3 — Principal design approach of logical evaluation
Figure F.4 — Example of logical representation (program sketch)
Figure H.1 — Subsystem A logical representation
Figure H.2 — Subsystem B logical representation
Figure H.3 — Subsystem C logical representation
Figure H.4 — Correlation of subsystem C and the pertinent fault handling function
Figure H.5 — Subsystem C with external fault handling function
Figure H.6 — Subsystem C with external fault diagnostics
Figure H.7 — Subsystem C with external fault reaction
Figure H.8 — Subsystem C with internal fault diagnostics and internal fault reaction
Figure H.9 — Subsystem D logical representation
Figure I.1 — Example of a machine design plan including a safety plan
Figure I.2 — Example of activities, documents and roles
Figure H.4 — Correlation of basic subsystem architecture C and the pertinent fault handling function
Table 1 — Terms used in IEC 62061
Table 2 — Abbreviations used in IEC 62061
Table 3 — SIL and limits of PFH values
Table 4 — Required SIL and PFH of pre-designed subsystem
Table 5 — Relevant information for each subsystem
Table 6 — Architectural constraints on a subsystem: maximum SIL that can be claimed for an SCS using the subsystem
Table 7 — Overview of basic requirements and interrelation to basic subsystem architectures
Table 8 — Different levels of application software
Table 9 — Documentation of an SCS
Table A.1 — Severity (Se) classification
Table A.2 — Frequency and duration of exposure (Fr) classification
Table A.3 — Probability (Pr) classification
Table A.4 — Probability of avoiding or limiting harm (Av) classification
Table A.5 — Parameters used to determine class of probability of harm (Cl)
Table A.6 — Matrix assignment for determining the required SIL (or PLr) for a safety function
Table B.1 — Safety requirements specification – example of overview
Table B.2 — Systematic integrity – example of overview
Table B.3 — Verification by tests
Table C.1 — Standards references and MTTFD or B10D values for components
Table D.1 — Estimates for diagnostic coverage (DC)
Table E.1 — Criteria for estimation of CCF
Table E.2 — Criteria for estimation of CCF
Table F.1 — Example of relevant documents related to the simplified V-model
Table F.2 — Examples of coding guidelines
Table F.3 — Specified safety functions
Table F.4 — Relevant list of input and output signals
Table F.5 — Example of simplified cause and effect matrix
Table F.6 — Verification of software system design specification
Table F.7 — Software code review
Table F.8 — Software validation
Table G.1 — Examples of typical safety functions
Table H.1 — Allocation of PFH value of a subsystem
Table H.2 — Relationship between B10D, operations and MTTFD
Table H.3 — Minimum value of 1/λD FH for the applicability of PFHequation (H.4)
Table J.1 — Minimum levels of independence for review, testing and verification activities
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AS/NZS 62061:2025 Safety of machinery - Functional safety of safety-related control systems
Preface
FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms, definitions and abbreviations
3.1 Alphabetical list of definitions
3.2 Terms and definitions
3.3 Abbreviations
4 Design process of an SCS and management of functional safety
4.1 Objective
4.2 Design process
4.3 Management of functional safety using a functional safety plan
4.4 Configuration management
4.5 Modification
5 Specification of a safety function
5.1 Objective
5.2 Safety requirements specification (SRS)
5.2.1 General
5.2.2 Information to be available
5.2.3 Functional requirements specification
5.2.4 Estimation of demand mode of operation
5.2.5 Safety integrity requirements specification
6 Design of an SCS
6.1 General
6.2 Subsystem architecture based on top down decomposition
6.3 Basic methodology – Use of subsystem
6.3.1 General
6.3.2 SCS decomposition
6.3.3 Sub-function allocation
6.3.4 Use of a pre-designed subsystem
6.4 Determination of safety integrity of the SCS
6.4.1 General
6.4.2 PFH
6.5 Requirements for systematic safety integrity of the SCS
6.5.1 Requirements for the avoidance of systematic hardware failures
6.5.2 Requirements for the control of systematic faults
6.6 Electromagnetic immunity
6.7 Software based manual parameterization
6.7.1 General
6.7.2 Influences on safety-related parameters
6.7.3 Requirements for software based manual parameterization
6.7.4 Verification of the parameterization tool
6.7.5 Performance of software based manual parameterization
6.8 Security aspects
6.9 Aspects of periodic testing
7 Design and development of a subsystem
7.1 General
7.2 Subsystem architecture design
7.3 Requirements for the selection and design of subsystem and subsystem elements
7.3.1 General
7.3.2 Systematic integrity
7.3.3 Fault consideration and fault exclusion
7.3.4 Failure rate of subsystem element
7.4 Architectural constraints of a subsystem
7.4.1 General
7.4.2 Estimation of safe failure fraction (SFF)
7.4.3 Behaviour (of the SCS) on detection of a fault in a subsystem
7.4.4 Realization of diagnostic functions
7.5 Subsystem design architectures
7.5.1 General
7.5.2 Basic subsystem architectures
7.5.3 Basic requirements
7.6 PFH of subsystems
7.6.1 General
7.6.2 Methods to estimate the PFH of a subsystem
7.6.3 Simplified approach to estimation of contribution of common cause failure (CCF)
8 Software
8.1 General
8.2 Definition of software levels
8.3 Software – Level 1
8.3.1 Software safety lifecycle – SW level 1
8.3.2 Software design – SW level 1
8.3.3 Module design – SW level 1
8.3.4 Coding – SW level 1
8.3.5 Module test – SW level 1
8.3.6 Software testing – SW level 1
8.3.7 Documentation – SW level 1
8.3.8 Configuration and modification management process – SW level 1
8.4 Software level 2
8.4.1 Software safety lifecycle – SW level 2
8.4.2 Software design – SW level 2
8.4.3 Software system design – SW level 2
8.4.4 Module design – SW level 2
8.4.5 Coding – SW level 2
8.4.6 Module test – SW level 2
8.4.7 Software integration testing SW level 2
8.4.8 Software testing SW level 2
8.4.9 Documentation – SW level 2
8.4.10 Configuration and modification management process – SW level 2
9 Validation
9.1 Validation principles
9.1.1 Validation plan
9.1.2 Use of generic fault lists
9.1.3 Specific fault lists
9.1.4 Information for validation
9.1.5 Validation record
9.2 Analysis as part of validation
9.2.1 General
9.2.2 Analysis techniques
9.2.3 Verification of safety requirements specification (SRS)
9.3 Testing as part of validation
9.3.1 General
9.3.2 Measurement accuracy
9.3.3 More stringent requirements
9.3.4 Test samples
9.4 Validation of the safety function
9.4.1 General
9.4.2 Analysis and testing
9.5 Validation of the safety integrity of the SCS
9.5.1 General
9.5.2 Validation of subsystem(s)
9.5.3 Validation of measures against systematic failures
9.5.4 Validation of safety-related software
9.5.5 Validation of combination of subsystems
10 Documentation
10.1 General
10.2 Technical documentation
10.3 Information for use of the SCS
10.3.1 General
10.3.2 Information for use given by the manufacturer of subsystems
10.3.3 Information for use given by the SCS integrator
Annex A (informative) Determination of required safety integrity
Annex B (informative) Example of SCS design methodology
Annex C (informative) Examples of MTTFD values for single components
Annex D (informative) Examples for diagnostic coverage (DC)
Annex E (informative) Methodology for the estimation of susceptibility to common cause failures (CCF)
Annex F (informative) Guideline for software level 1
Annex G (informative) Examples of safety functions
Annex H (informative) Simplified approaches to evaluate the PFH value of a subsystem
Annex I (informative) The functional safety plan and design activities
Annex J (informative) Independence for reviews and testing/verification/validation activities
Bibliography
Amendment 1
Figure 1 — Scope of this document
Figure 2 — Integration within the risk reduction process of ISO 12100 (extract)
Figure 3 — Iterative process for design of the safety-related control system
Figure 4 — Example of a combination of subsystems as one SCS
Figure 5 — By activating a low demand safety function at least once per year it can be assumed to be high demand
Figure 6 — Examples of typical decomposition of a safety function into sub-functions and its allocation to subsystems
Figure 7 — Example of safety integrity of a safety function based on allocated subsystems as one SCS
Figure 8 — Subsystem A logical representation
Figure 9 — Subsystem B logical representation
Figure 10 — Subsystem C logical representation
Figure 11 — Subsystem D logical representation
Figure 12 — V-model for SW level 1
Figure 13 — V-model for software modules customized by the designer for SW level 1
Figure 14 — V-model of software safety lifecycle for SW level 2
Figure 15 — Overview of the validation process
Figure A.1 — Parameters used in risk estimation
Figure A.2 — Example proforma for SIL assignment process
Figure B.1 — Decomposition of the safety function
Figure B.2 — Overview of design of the subsystems of the SCS
Figure F.1 — Plant sketch
Figure F.2 — Principal module architecture design
Figure F.3 — Principal design approach of logical evaluation
Figure F.4 — Example of logical representation (program sketch)
Figure H.1 — Subsystem A logical representation
Figure H.2 — Subsystem B logical representation
Figure H.3 — Subsystem C logical representation
Figure H.4 — Correlation of subsystem C and the pertinent fault handling function
Figure H.5 — Subsystem C with external fault handling function
Figure H.6 — Subsystem C with external fault diagnostics
Figure H.7 — Subsystem C with external fault reaction
Figure H.8 — Subsystem C with internal fault diagnostics and internal fault reaction
Figure H.9 — Subsystem D logical representation
Figure I.1 — Example of a machine design plan including a safety plan
Figure I.2 — Example of activities, documents and roles
Figure H.4 — Correlation of basic subsystem architecture C and the pertinent fault handling function
Table 1 — Terms used in IEC 62061
Table 2 — Abbreviations used in IEC 62061
Table 3 — SIL and limits of PFH values
Table 4 — Required SIL and PFH of pre-designed subsystem
Table 5 — Relevant information for each subsystem
Table 6 — Architectural constraints on a subsystem: maximum SIL that can be claimed for an SCS using the subsystem
Table 7 — Overview of basic requirements and interrelation to basic subsystem architectures
Table 8 — Different levels of application software
Table 9 — Documentation of an SCS
Table A.1 — Severity (Se) classification
Table A.2 — Frequency and duration of exposure (Fr) classification
Table A.3 — Probability (Pr) classification
Table A.4 — Probability of avoiding or limiting harm (Av) classification
Table A.5 — Parameters used to determine class of probability of harm (Cl)
Table A.6 — Matrix assignment for determining the required SIL (or PLr) for a safety function
Table B.1 — Safety requirements specification – example of overview
Table B.2 — Systematic integrity – example of overview
Table B.3 — Verification by tests
Table C.1 — Standards references and MTTFD or B10D values for components
Table D.1 — Estimates for diagnostic coverage (DC)
Table E.1 — Criteria for estimation of CCF
Table E.2 — Criteria for estimation of CCF
Table F.1 — Example of relevant documents related to the simplified V-model
Table F.2 — Examples of coding guidelines
Table F.3 — Specified safety functions
Table F.4 — Relevant list of input and output signals
Table F.5 — Example of simplified cause and effect matrix
Table F.6 — Verification of software system design specification
Table F.7 — Software code review
Table F.8 — Software validation
Table G.1 — Examples of typical safety functions
Table H.1 — Allocation of PFH value of a subsystem
Table H.2 — Relationship between B10D, operations and MTTFD
Table H.3 — Minimum value of 1/λD FH for the applicability of PFHequation (H.4)
Table J.1 — Minimum levels of independence for review, testing and verification activities
AS/NZS 62061:2025
Online Library subscription information
Online library subscriptions provide a cost-effective solution for organisations of any size to access the latest standards, offering 24/7 access to a personalised catalogue. The service ensures subscribers have have the most up-to-date version of selected standards, incluing automatic updates for any amendments or versions. Pricing is dependent on the chosen standards and the number of concurrent users, with discounts applied from the standards PDF price. For customised subscriptions or further inquiries, contact the Online Library team.