AiVibeISO 13849 and Performance Level (PL)
ISO 13849 is the international standard for safety-related parts of machine control systems, in which the ability of each safety function to perform under foreseeable conditions is expressed as a Performance Level from PL a, the lowest, to PL e, the highest.
ISO 13849-1 covers design principles and ISO 13849-2 covers validation. The required Performance Level (PLr) for a safety function is determined from the risk, using the severity of injury, the frequency or duration of exposure and the possibility of avoiding the hazard, often with a risk graph. The achieved PL depends on the designated architecture category (B, 1, 2, 3 or 4), the mean time to dangerous failure (MTTFD) of components, diagnostic coverage (DC) and measures against common cause failures.
ISO 13849 is technology-neutral, covering electrical, hydraulic, pneumatic and mechanical safety-related parts, which makes it widely used by machine builders. Typical safety functions include emergency stop, guard interlocking, safe speed monitoring and muting. Component manufacturers publish data such as PL, category, MTTFD or PFHD to support the calculation.
Designers verify that the achieved PL meets or exceeds PLr for each safety function, commonly using calculation tools such as the IFA's SISTEMA software, and then validate the function through analysis and testing, including fault considerations. The standard sits alongside IEC 62061, and both start from a risk assessment according to ISO 12100. Design and validation of safety functions must be carried out by competent, qualified personnel.
Key points
- Covers safety-related parts of machine control systems of any technology
- Performance Levels range from PL a (lowest) to PL e (highest)
- Required PL is set from severity, exposure and possibility of avoidance
- Achieved PL depends on category, MTTFD, diagnostic coverage and CCF
- Part 1 covers design principles; part 2 covers validation
Where AiVibe comes in
AiVibe designs and manufactures the AiAmbA AI Factory, whose edge devices and AI agents let people talk to PLC, CNC and robot controllers in plain language. Agents only propose changes, a trained operator confirms each one, and the AI Factory never replaces a machine's control or safety systems.
Related terms
- IEC 62061PLC & Industrial Control
- Functional SafetyPLC & Industrial Control
- Safety PLCPLC & Industrial Control
- InterlockPLC & Industrial Control
- Safe Torque Off (STO)PLC & Industrial Control
- Safety Integrity Level (SIL)PLC & Industrial Control