The D4SL-N4HFA-DN is a guard lock safety-door switch from Omron, designed to interlock and lock access doors on machinery with a solenoid-release mechanism. The built-in switch configuration is 3NC + 2NC, giving two separate safety channels plus a third NC contact for status feedback or secondary monitoring. The solenoid release is 24 VDC (orange LED indicator confirms power present), and the door lock is mechanical — meaning the lock holds even if power is lost, and the solenoid releases to allow door opening only when energized. This is a standard fail-safe approach for guarding zones where unintended door opening during motion is a hazard. The head is resin, the conduit outlet is M20, and the connection method is via connector (not a cable gland). The release key is standard metal. This switch fits applications like machine tool guarding, packaging lines, and robotic cell access points where a positive-locked door is required per ISO 14119.
Wiring and Installation
M20 conduit entry suits standard metric gland plates. The connector style means the switch body can be replaced without rewiring the panel — unplug the old, plug in the new. The 3NC + 2NC arrangement: wire the two NC safety channels in series with the safety relay or controller inputs; the third NC can serve as a diagnostic feedback to a PLC. The 24 VDC solenoid draws power from a standard control transformer or PELV supply. The orange LED on the indicator confirms the solenoid is energized and the door is unlocked — a quick visual check during commissioning or fault-finding.