Use ISO 13849-1 to establish the safety architecture and Performance Level, then use ISO 13849-2 to validate the specified safety functions through analysis and testing [S1][S2].
The split is functional: ISO 13849-1 addresses design principles, system requirements, categories and Performance Levels, whereas ISO 13849-2 covers validation procedures and conditions for the specified safety functions [S1][S2].
ISO 13849-1 defines the safety design basis
ISO 13849-1 is the design and risk-reduction standard for safety-related parts of machinery control systems. Its purpose is to provide the basis for selecting and designing the architecture, parameters and Performance Level needed to meet the machinery's overall safety requirements [S3][S4].
Performance Level selection belongs to the design stage. The design must address the required safety functions, their risk parameters, the control-system architecture, the Category, and the required PL, while Part 2 supplies the method for proving that the implemented design achieves those requirements [S1][S3].
ISO 13849-2 proves the design through validation
ISO 13849-2:2012 specifies procedures and conditions for validating the specified safety functions by analysis and testing [S2]. The validation process confirms that the design of the SRP/CS supports the overall safety requirements specification for the machinery [S3].
Validation is therefore an evidence activity, not an alternative design method. Engineers must show that the selected Category, the achieved Performance Level, the diagnostic coverage, the fault-response behavior and the implemented safety functions correspond to the design assumptions used for risk reduction [S1][S3].
Design and validation must remain linked
The two standards form one controlled process: Part 1 sets the intended architecture and performance basis, and Part 2 tests whether that basis is realized by the actual machine [S1][S2]. A calculation performed only in the design file is not evidence that the installed system passes the required validation procedure.
A defensible validation package links each safety function to its risk parameters, safety requirements, architecture, Category, PL, analysis results, test cases and acceptance criteria. ISO 13849-1 is the basis for determining the Performance Level [S4].
Comparison by engineering decision
ISO 13849-1 is the correct source when the question is what the safety-related control system must contain and how its architecture must be designed. ISO 13849-2 is the correct source when the question is whether the specified safety functions have been adequately analyzed and tested [S1][S2].
For architecture and PL determination, Part 1 supplies the design framework while Part 2 provides the validation procedure. For fault evaluation, Part 2 contains the referenced tables [S4]. For test evidence, Part 1 cannot replace the analysis-and-testing requirements of Part 2 [S2]. For standalone procurement, neither part is a substitute for a machine-specific risk assessment and safety requirements specification [S3].
Where validation belongs in the machine lifecycle
Use ISO 13849-1 during concept definition, architecture selection and detailed design, then apply ISO 13849-2 when the SRP/CS and its safety functions are sufficiently defined for evaluation by analysis and testing [S1][S2]. This sequence prevents validation from becoming an informal check after construction.
For a broader framework decision where both electrical and hydraulic machinery may apply, compare ISO 13849 vs IEC 62061 for Machine Safety. ISO 13849-1 versus ISO 13849-2 is a narrower question: one part defines the design basis, and the other validates that basis.
Common failure modes and evidence gaps
A frequent failure is treating the Category or PL label as validation by itself. A claimed PL is not an acceptable substitute for the analysis and test evidence required by ISO 13849-2:2012 [S2][S3]. The validation record must demonstrate that the implemented safety functions satisfy the stated conditions.
Another failure is copying a generic software-validation example without demonstrating the fault evaluation for the actual configuration. Fault-evaluation tables are located in ISO 13849-2, while Part 1 provides the basis for Performance Level [S4].
A third failure is validating isolated components rather than the relevant SRP/CS architecture. The validation objective is to confirm support for the overall machinery safety requirements specification, not merely to prove that one safety relay, controller or sensor is operational [S3].
Standards scope and document control
EN ISO 13849-2:2012 was approved by CEN on 14 October 2012 and superseded EN ISO 13849-2:2008; the national-standard transition extended to April 2013 [S2]. The cited European edition identifies the subject as “Safety of machinery, Safety-related parts of control systems, Part 2: Validation,” based on ISO 13849-2:2012 [S2].
Record the exact edition used in the safety file, including the applicable ISO or EN designation and edition year. For cross-border machine programs, also record the jurisdiction's adopted standard, since EN ISO 13849-2:2012 is the European adoption identified in the cited catalogue entry [S2].
The next trackable engineering step is to produce one traceability row per safety function linking the risk parameters, safety requirements, Part 1 design parameters, Part 2 analysis, test evidence and approved result, then verify that every required PL has an objective evidence package before release.