The Omron D4SL-N4EFA-D4 is a guard lock safety-door switch — a solenoid-locked interlock that prevents access to a guarded area until safe conditions are met. The mechanical lock holds the door closed; the 24 VDC solenoid releases it when the safety circuit permits. The built-in switch configuration is 2NC/1NO + 1NC/1NO, giving two independent normally-closed safety channels plus a normally-open auxiliary for status feedback.
The 24 VDC solenoid release (indicated by the orange LED on the switch body) means this unit is wired into a 24 VDC safety circuit — standard for most PLC-based safety systems. The M20 conduit outlet accepts standard metric cable glands, so panel integration is straightforward with no adapter needed. The resin head is suited for environments where corrosion resistance matters more than impact strength; if the application sees repeated mechanical abuse, a metal-head variant would be the alternative.