What signal does the through-beam sensor send to the PLC when no part is present?

The through-beam sensor operates on the principle of detecting the interruption of a light beam, which is typically emitted continuously from a transmitter to a receiver. When no part is present in the sensing area, the light beam reaches the receiver without any obstruction.

In this scenario, the signal generated by the sensor upon receiving the uninterrupted light beam is generally a high signal. This is because the sensor is designed to indicate that the path is clear, thus sending a high signal to the PLC (Programmable Logic Controller) to indicate the absence of an object.

This high signal can be interpreted by the PLC as an indication that it can proceed with normal operations or that there are no parts to process, depending on the automation logic established in the system. This makes the understanding of the sensor's output essential for programming and responding to the presence or absence of materials in automated processes.