The Siemens 3SF7844-8BD22-1SS1 is a Type 4 safety light curtain host receiver from the SIMATIC FS420I family, with 30 mm resolution and a 1500 mm protective height. It supports blanking and operates over a 0 to 18 m range, communicating via PROFIsafe bus connection. Type 4 per IEC 61496-1/2 means it is rated for the highest level of fault tolerance and reliability in safety light curtains — suitable for guarding hazardous zones where a failure must not lead to loss of safety function.
30 mm resolution catches fingers reaching into the hazard zone (finger-protection class per IEC 61496-1). The 1500 mm protective height covers a typical machine opening up to waist height; the 0 to 18 m range gives flexibility for longer guarding distances without adding a second curtain. Blanking allows fixed or floating objects (e.g., a workpiece carrier) to pass through the field without triggering a stop — useful on assembly or palletizing lines where the curtain must ignore a part fixture. PROFIsafe bus connection integrates directly into a Siemens safety PLC (e.g., ET 200SP F or S7-1500 F) without a separate safety relay module.