Type 4 Safety Light Curtain Receiver
The Siemens 3SF7844-8MD06-0SS1 is a Type 4 standard receiver from the SIMATIC FS420I safety light curtain family. It offers a 30 mm resolution and a 450 mm protected height, with a sensing range of 0 to 18 meters. This receiver is designed for integration into safety circuits requiring a PROFIsafe bus connection, supporting muting functions for material handling applications where the safety field must be temporarily bypassed during normal production flow.
The 30 mm resolution means this curtain detects objects as small as 30 mm in diameter — typically a hand or finger. This classifies it as finger-protection per IEC 61496-2, suitable for guarding access points where personnel might reach into a hazard zone. The 450 mm protected height defines the vertical coverage; pair it with a matching emitter of the same height. The 0 to 18 m range covers most machine guarding layouts, from compact stations to longer conveyor lines. The Type 4 designation (per IEC 61496-1) means the system is rated for the highest safety integrity — capable of detecting single faults and maintaining the safety function.
Deployment Context
Mount the receiver on a machine guard or stand-off bracket, aligned optically with the corresponding emitter. The PROFIsafe bus connection ties directly into a SIMATIC safety controller (e.g., F-CPU via the FS420I interface module), eliminating the need for a separate safety relay for each curtain. The muting function uses external sensors to signal the curtain when a workpiece — but not a person — is passing through the field, keeping the machine running during normal material flow. This is common on assembly lines, packaging machines, and robotic cells where product must enter and exit the guarded area without stopping the cycle.