Field note on the E3FB-DP21
This is an Omron M18 cylindrical diffuse photoelectric sensor, part of the E3FB series. It uses a red light beam and detects opaque objects as small as 7 mm diameter at up to 100 mm. Output is PNP, switching 100 mA max from a 10-30 VDC supply. Connections are through a 4-pin M12 connector. The brass body is sealed IP67/IP69K so it handles hot washdown cycles.
vs. E3FB-DP23 – what changes
The E3FB-DP23 is the same sensor but with a 1 m sensing distance instead of 100 mm. Everything else – M12 connector, 4-pin PNP wiring, supply range, body material, protection, IP rating – is identical. If your panel was built around the DP23, the DP21 will mechanically and electrically drop in. The only difference is how far it can see. If your target sits beyond 100 mm, the DP21 won't trigger. Measure your target location before swapping.
Built-in ruggedness
The sensor carries output short-circuit protection, output reverse polarity protection, and power supply reverse polarity protection. That means fewer blown outputs from wiring mistakes. The IP67/IP69K seal means you can hose it down at high pressure without worrying about ingress. CE marked.