Safety light curtain receiver for guarded access
The Siemens 3SF7844-8MD08-0SS1 is a Type 4 safety light curtain receiver from the SIMATIC FS420I family, designed for guarding hazardous zones on automated machinery. It provides a 30 mm resolution over a 600 mm protective height, with a sensing range of 0 to 18 m, and integrates muting functionality for material handling passes. Communication is via Profisafe bus connection, making it a direct fit into Siemens safety-oriented control architectures.
Type 4 per IEC 61496-1/2 is the highest safety integrity level for electro-sensitive protective equipment — it can be used for applications up to SIL 3 / PL e. The 30 mm resolution means the curtain detects fingers (30 mm is the minimum object size that will be reliably detected), so it suits point-of-operation guarding where hand access must be prevented. The 600 mm protective height covers a typical vertical opening for small to mid-size machine access points. Muting capability allows the curtain to be temporarily overridden during a workpiece pass-through without stopping the machine, which is essential for automated material handling lines.
Integration with SIMATIC FS420I and Profisafe
This receiver is part of the SIMATIC FS420I system and communicates over Profisafe, the safety-oriented bus protocol that runs on PROFINET. No separate safety relay is needed — the safety signals are transmitted directly to a failsafe controller (e.g., SIMATIC S7-1200F or S7-1500F). The 0 to 18 m range covers long access zones; the actual maximum range depends on the paired emitter and ambient conditions. Mounting hardware and alignment aids are standard for the FS420I family.