The Siemens 3SF7844-6TD04-0SS1 is a Type 4 safety light curtain receiver from the SIMATIC FS440I family, with 30 mm resolution and a 300 mm protective height covering a 0 to 18 m operating range. It connects via ASISAFE bus, which means it integrates directly into a safety-rated fieldbus loop without a separate safety relay — the safety logic lives in the FS440I controller or a failsafe PLC. Type 4 per IEC 61496-1/2 means it catches fingers reaching into the hazard zone and is rated for the highest level of fault tolerance and detection reliability in light curtain design.
Deployment Context
Mounts as the receiver half of a Type 4 safety light curtain guarding a 300 mm tall zone. The 30 mm resolution detects a 30 mm object — typically a hand or finger — anywhere in the 0 to 18 m range. ASISAFE bus eliminates the need for a separate interface module; the safety data runs directly to the FS440I controller or a SIMATIC failsafe PLC over the bus cable. Alignment and commissioning follow the standard two-person procedure: one at the emitter, one at the receiver, with the bus providing diagnostic feedback on beam status.