Safety Light Curtain Type 4 Host Receiver — 14 mm, 300 mm, PROFIsafe
The Siemens 3SF7844-8TB04-1SS1 is a Type 4 safety light curtain host receiver from the SIMATIC FS420I series. It provides a 14 mm detection resolution over a 300 mm protected height, with an operating range of 0 to 6 m. The PROFIsafe bus connection integrates directly into a safety-oriented automation network — no separate safety relay needed for the bus interface. Type 4 per IEC 61496-1/2 is the highest category for electro-sensitive protective equipment: it can tolerate a single fault without losing the safety function. The 14 mm resolution means it detects fingers reaching into the hazard zone (finger-protection class), so it suits press brakes, assembly stations, and robotic cells where hand access must be caught.
Deployment Context — PROFIsafe Integration
This receiver is the host unit in a Type 4 light curtain pair; it processes the emitter beam pattern and communicates the safety status over PROFIsafe. The 0 to 6 m range covers typical guarding distances for medium-sized machinery. Cycle control is built in — the receiver handles the restart interlock and blanking logic internally, reducing PLC safety-program complexity. Mount the receiver and its paired emitter on the machine frame or guarding stanchions. The 300 mm height covers a vertical zone that matches common panel openings or machine apertures. No separate bus coupler is required — the PROFIsafe connection is integral, saving a slot in the safety I/O rack.