Performance level (PL)

Performance level is the discrete measure defined in ISO 13849-1 for the ability of a safety-related control function to perform under foreseeable conditions, graded from PL a (lowest) to PL e (highest). The required PL for each safety function is determined from the risk assessment, and the achieved PL is calculated from the architecture, reliability data, and diagnostic coverage of the implementing hardware. It is the ISO 13849 counterpart to the safety integrity level (SIL) used by IEC 62061.

Standard
ISO 13849-1:2023, International Organization for Standardization (2023)