SICK L21E-21MA1A Single Beam Photoelectric Safety Switch

The L21E-21MA1A is the receiver unit in SICK’s L21 single-beam safety switch family, designed for 24 V DC operation with axial optics and a 16 m scanning range for safety interlock applications. It features a 4‑pin M12 straight connector and is intended to be paired with the L21S sender to form a safety light-beam sensor; it supports safe operation in Type 2 IEC 61496-1 and PL c EN ISO 13849-1 environments, with SIL 1 per IEC 61508 when used with a compliant safety controller (e.g., SICK Flexi Classic or Flexi Soft). The device responds in 0.2 ms and provides local status via color LEDs, aiding quick diagnostics on the machine floor. Electrical and environmental specs include 19.2–28.8 V DC supply (nominal 24 V), IP67 enclosure protection, and a wide operating temperature range of -40 °C to +55 °C. Safety performance is quantified by a PFH of 1.0 × 10^-6 per hour, a maximum demand rate of 60 min^-1, and a test rate (external) of 100 s^-1, with an achievable mission time of up to 20 years when used with an appropriate test device. The receiver is designed for safety-critical automation, offering short-circuit protection and compliance with IEC/EN safety standards, and relies on a compatible safety controller to achieve higher PL levels.