The Festo SOEG-RTH-M18-PS-S-2L is a diffuse photoelectric sensor in an M18 threaded barrel — a standard form factor for mounting through brackets or direct into machine frames. Diffuse mode means the emitter and receiver share the same housing; the sensor detects objects by the light reflected back from the target itself, no separate reflector required. This makes it a straightforward pick for presence detection on conveyors, part-verification stations, or level monitoring in packaging lines where the target surface offers enough reflectivity.
The M18 barrel diameter is the critical mechanical fit dimension — it determines the mounting hole size and bracket compatibility. The PNP switching output (PS in the order code) is the standard sourcing configuration for most PLC digital inputs; verify your input card sinks or sources accordingly. Diffuse sensing range depends on target reflectivity, so a matte-black object will be detected at a shorter distance than a white or reflective one — factor that into your sensing gap calculation.