The Omron D4SLN4NFADN is a guard-locking safety-door switch from the D4SL series, built for interlocking access on machinery where the guard must stay locked until conditions are safe. It uses a key-actuated head with four direction options, so you can mount it top, bottom, left, or right depending on the door swing. Contact arrangement is 2NO + 4NC — the normally-open pair drives the machine control circuit, the four normally-closed contacts feed the safety chain. That's a lot of NC contacts for one switch; it gives you room to wire multiple safety relays or a dual-channel safety PLC input without adding auxiliary blocks. IP67 rating means the switch body and head handle washdown and dust — out here in the grease, that's what keeps a guard switch from failing when the hose hits it. Connector termination speeds replacement; no need to re-terminate individual wires inside the panel.
Switching ratings and life
Switching capacity is 1.5 A at 120 V AC and 220 mA at 125 V DC. That's plenty for pilot-duty control circuits — think safety relay coils, PLC inputs, or contactor auxiliaries. Don't plan on switching motor loads directly; this is a signal-level interface. Electrical life is rated at 150,000 cycles, mechanical life at 1 million cycles. The gap tells you the contacts wear before the mechanism does. In a high-cycle application — say a robot cell door opening every 30 seconds — the electrical life will be the limit, not the lock mechanism.