How to wire four fiber optic sensors

A typical four-wire fiber optic sensor uses brown and blue for power, black for signal output, and a fourth wire (often white) for additional signal or control, connected according to the sensor's specifications.

Wire Identification and Connections

Brown Wire (24V DC): Connect this wire to the positive terminal of a 24V DC power supply to provide the sensor with operating voltage. Blue Wire (0V / Ground): Connect this wire to the negative terminal of the power supply to complete the circuit. Black Wire (Signal Output): This wire typically carries the output signal from the sensor.

Connect it to the input of a relay, PLC, or other control device. Ensure the device is compatible with the sensor's output type (NPN or PNP),. Fourth Wire (White or Optional): Some sensors include a fourth wire for additional functions such as a second output, analog signal, or control input.

Refer to the sensor's datasheet to determine its exact function and connection requirements.

Setup Tips

Power Supply: Use a stable 24V DC switching power supply to avoid voltage fluctuations that could affect sensor performance. Signal Configuration: Many fiber optic sensors allow you to select DARK-ON or LIGHT-ON modes, which determine whether the output is active when the light beam is blocked or received. Fiber Alignment: Ensure the fiber optic cable is properly aligned with the transmitter (T) and receiver (R) ends.

Misalignment can prevent the sensor from detecting objects correctly. Calibration: After wiring, calibrate the sensor by setting the reference light intensity for detection. Typically, you press the SET key at the farthest and closest positions of the target object to define the trigger threshold.

Safety and Best Practices

Avoid running fiber optic cables alongside high-voltage lines to prevent interference. Do not bend the fiber optic cable below the minimum bend radius to maintain signal integrity. Verify all connections before powering the sensor to prevent short circuits or damage.

By following these steps, the four-wire fiber optic sensor can be safely connected and configured for accurate detection and reliable operation.