What you're working with
The E2B-M30KN20-M1-C2: M30 barrel, unshielded — so it can detect through thin stainless or plastic sheet if you need to mount it behind a guard. Let me show you why that matters: the 20 mm sensing range is rated on steel, but you'll get almost that same distance through a non-ferrous layer up to about 3 mm thick. Just keep the face clear of metal buildup. NPN output, normally closed. Ask the dumb question now: does NC mean the output is on when nothing's there? Yes. That gives you a fail-safe — if the sensor loses power or the wire breaks, the signal drops, and the PLC sees a 'target present' even though nothing's there. Good for safety interlocks or presence verification on a conveyor. Operates on 12 to 24 VDC supply.
M30 thread, 29 mm threaded length, 64 mm overall. M12 4-pin connector. Case is nickel-plated brass — good corrosion resistance for washdown areas, but don't let the connector face sit in standing water. The brass body also gives you a solid ground path through the mounting bracket if your panel uses the machine frame as a reference.