Schmersal SRB-402EM 4-Channel Safety Relay Module

The Schmersal SRB-402EM is a four‑channel safety relay extension module that adds four safety contacts (STOP 0) and two signalling outputs to Schmersal’s PROTECT safety system, enabling expanded, multi‑channel safety evaluation for machinery. Designed as an output expander, it supports safe signal evaluation in safety circuits and is compatible with the SRB safety family for use in category 0/1 E‑STOP configurations. It operates from a 24 VDC supply and carries robust safety ratings, including EN ISO 13849‑1, IEC 61508, and EN 60947‑5‑1, with a control category up to 4, PFH ≤ 2.0 × 10⁻⁸ /h for STOP 0, and a SIL rating up to 3, along with an estimated service life of 20 years. The unit measures 120 × 22.5 × 121 mm (H × W × D), making it a compact fit for tight control cabinets while delivering four safe outputs and two auxiliary signalling paths. Typical applications include expanding safety contact networks for safe stop/start logic, integrating additional E‑STOP circuits, and enabling reliable multi‑channel safety signaling in industrial machines where space and safety integrity are critical. This module is intended to be deployed in safety‑critical environments where precise, verifiable safe signal evaluation is required to meet stringent standards and ensure consistent fail‑safe performance across multiple safety channels.