SIST EN 62061:2021/A2:2026

• Status: Not Published
• Public Enquiry End Date: 30-May-2025
• ICS: 13.110 - Safety of machinery
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 25.040.99 - Other industrial automation systems
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: MOV - Measuring equipment for electromagnetic quantities
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 30-Jun-2026
• Due Date: 04-Sep-2026
• Directive: 2006/42/EC - Directive 2006/42/EC of the European Parliament and of the Council of 17 May 2006 on machinery, and amending Directive 95/16/EC (recast)
• Mandate: M/396 - Mandate to CEN and Cenelec for standardisation in the field of machinery
• Ref Project: EN IEC 62061:2021/A2:2026 - Safety of machinery - Functional safety of safety-related control systems

• Amends: SIST EN IEC 62061:2021 - Safety of machinery - Functional safety of safety-related control systems (IEC 62061:2021)
• Effective Date: 19-Mar-2024

SIST EN 62061:2021/A2:2026 is the Slovenian adoption of Amendment 2 to IEC 62061:2021, under the title Safety of machinery - Functional safety of safety-related control systems. It updates the machinery safety rules for functional safety of safety-related control systems (SCS), mainly in the areas of diagnostic functions, fault reaction, and isolated faulty channels. It is meant for engineers, assessors, and buyers who need to apply or check the safety logic used in machine control systems.

What does SIST EN 62061:2021/A2:2026 specify?

SIST EN 62061:2021/A2:2026 specifies amendments to the base standard for safety-related control systems in machinery. It does not stand alone as a full replacement text - it updates selected clauses, a table note, and a figure in IEC 62061:2021.

Affected part	What this amendment changes
7.4.1 General	Updates the table reference and revises the note on when certain subsystems can achieve SIL 1
7.4.3.1 General	Replaces the text on diagnostic detection, fault reaction, and restart conditions
7.4.3.2 Fault reaction function	Renames the clause to isolation of a faulty channel of a subsystem and revises the conditions
7.4.4 Realization of diagnostic functions	Revises how diagnostic functions are treated in the simplified PFH approach
Table C.1	Updates the note on emergency stop devices and enabling switches
Figure I.2	Revises one role label

What are the key requirements of SIST EN 62061:2021/A2:2026?

This amendment tightens the link between diagnosis, fault reaction, and the safe state. In practice, it tells you when the machine must stop or isolate a faulty channel, when restart is blocked, and what evidence is needed for diagnostic functions.

Diagnostic detection and safe-state reaction

In 7.4.3.1, SIST EN 62061:2021/A2:2026 requires automatic diagnostic functions to trigger a specified fault reaction when a dangerous failure is detected in a subsystem with hardware fault tolerance (HFT) greater than zero. The aim is to reach or maintain a safe state before a dangerous situation can occur.

For zero-HFT subsystems that rely on diagnostics to achieve the required safe failure fraction, the amendment sets two practical options - a diagnostic test rate at least 100 times the demand rate, or testing immediately when the safety function is demanded. It also requires the combined detection and reaction time to be short enough for safety, and normal operation must stay blocked until repair.

Isolation of a faulty channel

In 7.4.3.2, the amendment allows isolation of a faulty channel in some machines instead of an immediate stop, but only for subsystems with HFT = 1 or higher. The machine may keep running only up to an estimated maximum isolation time, and if repair does not happen in time, a fault reaction function must bring the system to a safe state.

This matters where an immediate stop would create a bigger risk than controlled continued operation. The text points readers to measures such as speed reduction, blocking a dangerous area, or using a single-channel design that can still reach the target SIL.

Diagnostic functions and PFH

In 7.4.4, SIST EN 62061:2021/A2:2026 states that diagnostic functions must satisfy systematic safety integrity requirements. For the simplified PFH approach, the diagnostic functions should keep the probability of dangerous failure per hour (PFH) within the allowed PFH for the required SIL, or be no more than one order of magnitude worse with additional testing of diagnostic function operation.

For practice, this means the diagnostic function itself is not treated as a free add-on - it needs its own evidence, testing plan, and proof that it still works through the proof test interval.

Supporting notes and annex material

A revised note in Table C.1 explains how emergency stop devices and enabling switches can be treated as HFT = 0 or HFT = 1 subsystems depending on the number of electrical output contacts. That helps when selecting components for safety calculations. Figure I.2 also updates a role label used in the example activity and document flow.

What terms does SIST EN 62061:2021/A2:2026 define?

• Safety-related control system (SCS) - the control system that performs safety functions for machinery and must behave predictably when faults occur.
• Hardware fault tolerance (HFT) - the ability of a subsystem to tolerate faults while still performing its safety function.
• Safe failure fraction (SFF) - the share of failures that are safe or detected, used when judging whether a subsystem can support a required SIL.
• Safety integrity level (SIL) - the target level used to judge the reliability of the safety function.
• Probabilistic failure per hour (PFH) - the failure likelihood measure used here to check whether diagnostic functions fit the required SIL.
• Safe state - the condition the machine must reach or maintain to avoid a dangerous situation.
• Fault reaction function - the action taken after a dangerous fault is detected, such as stopping or isolating part of the system.

Who uses SIST EN 62061:2021/A2:2026?

SIST EN 62061:2021/A2:2026 is used by machine builders, control system designers, functional safety engineers, and validation teams working on machinery. Quality managers and buyers use it when they need to check whether a control system’s safety architecture, diagnostics, and restart logic are suitable for the intended machine.

It is especially relevant in industrial automation and other machinery sectors where safety-related control systems must be designed, assessed, and documented in a traceable way.

What changed in SIST EN 62061:2021/A2:2026 from the previous edition?

SIST EN 62061:2021/A2:2026 is Amendment 2 to IEC 62061:2021. The amendment changes these parts of the base standard:

• 7.4.1 - updates the table reference and the note on SIL 1 conditions
• 7.4.3.1 - replaces the requirements for diagnostic detection and restart blocking
• 7.4.3.2 - renames the clause and revises the rules for isolating a faulty channel
• 7.4.4 - revises the simplified PFH treatment of diagnostic functions
• Table C.1 - updates the note on emergency stop devices and enabling switches
• Figure I.2 - updates one role label in the example

Which standards are used with SIST EN 62061:2021/A2:2026?

• IEC 61508 - cited for further information on the development and validation of subsystems with isolated faulty channels.
• IEC 60947-5-5 - cited with emergency stop devices in the updated Table C.1 note.
• ISO 13850 - cited with emergency stop devices in the updated Table C.1 note.
• IEC 60947-5-8 - cited for enabling switches in the updated Table C.1 note.

What does the SIST EN 62061:2021/A2:2026 document contain?

The document contains amendment instructions that replace specific paragraphs, notes, and a subclause title in IEC 62061:2021. The main technical content is the updated language on diagnostic functions, fault reaction, isolation of a faulty channel, and the proof-testing treatment of diagnostics.

It also includes a foreword with publication and voting information, plus the targeted edits to Table C.1 and Figure I.2. For implementation work, the most useful parts are the rewritten requirements in 7.4.1, 7.4.3.1, 7.4.3.2, and 7.4.4.

SLOVENSKI STANDARD
SIST EN 62061:2021/oprA2:2025
01-maj-2025
Varnost strojev - Funkcijska varnost nadzornih sistemov, povezanih z varnostjo
Amendment 2 - Safety of machinery - Functional safety of safety-related control systems
Sicherheit von Maschinen - Funktionale Sicherheit sicherheitsbezogener
Steuerungssysteme
Amendement 2 - Sécurité des machines - Sécurité fonctionnelle des systèmes de
commande relatifs à la sécurité
Ta slovenski standard je istoveten z: EN 62061:2021/prA2:2025
ICS:
13.110 Varnost strojev Safety of machinery
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
SIST EN 62061:2021/oprA2:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

SIST EN 62061:2021/oprA2:2025
SIST EN 62061:2021/oprA2:2025
44/1058/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 62061/AMD2 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-03-28 2025-06-20
SUPERSEDES DOCUMENTS:
44/1027/CD, 44/1043A/CC
IEC TC 44 : SAFETY OF MACHINERY - ELECTROTECHNICAL ASPECTS
SECRETARIAT: SECRETARY:
United Kingdom Mrs Nyomee Hla-Shwe Tun
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
SC 65A
ASPECTS CONCERNED:
Safety
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some
Countries” clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is
the final stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Amendment 2 - Safety of machinery - Functional safety of safety-related control systems

PROPOSED STABILITY DATE: 2027
NOTE FROM TC/SC OFFICERS:
download this electronic file, to make a copy and to print out the content for the sole purpose of preparing National
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SIST EN 62061:2021/oprA2:2025
IEC CDV 62061/AMD2 ED2 © IEC 2025 2 44/1058/CDV
1 INTERNATIONAL ELECTROTECHNICAL COMMISSION
2 ____________
4 SAFETY OF MACHINERY –
5 FUNCTIONAL SAFETY OF SAFETY-RELATED CONTROL SYSTEMS
7 AMENDMENT 2
9 FOREWORD
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