What this slot sensor is and where it fits
The Omron EE-SX771R is a through-beam photoelectric sensor in a compact slot-style housing. It uses a PNP open-collector output configured Dark-ON — the output transistor turns on when the beam is blocked. The slot gap is 5 mm, so the target flag or vane must be thin enough to pass through without rubbing. Supply is fixed at 5 VDC; no wide-range input here. Mounting is via M3 screws directly to the chassis, which keeps alignment stable in vibration. The operating range of -25°C to 55°C suits indoor machine cabinets and conveyor lines, but not unheated outdoor enclosures or freezer tunnels.
PNP Dark-ON output — wiring and PLC compatibility
PNP Dark-ON means the output sinks current from the load to ground when the light path is interrupted. That's the opposite of the more common NPN Light-ON found on many general-purpose sensors. If your PLC input card expects NPN (sinking), you'll need a level shifter or a different sensor. The EE-SX771R sources current to the load when dark, so it mates directly with PNP (sourcing) input modules. The open-collector output can switch up to 30 mA — enough for a typical PLC digital input or a small relay, but not for direct solenoid drive.