En Iec 61496 [exclusive] -

| Parameter | Type 2 (Basic) | Type 4 (High) | | :--- | :--- | :--- | | | PL c (EN ISO 13849-1) / SIL 1 (EN 62061) | PL e / SIL 3 | | Fault Reaction | Loss of safety function at single fault (detected) | No loss of safety function at single fault | | MTTFd | Low to Medium | High | | Test Pulse Immunity | Standard | Rigorous (resistance to high-frequency pulses) |

Essential reading for machine safety. When sourcing equipment, never accept a generic "safety sensor" without verification of EN IEC 61496 compliance. en iec 61496