The sensor is designed to control the lateral displacement of the rim of the fabric during winding. The voltage at the sensor output is proportional to the position of the plate relative to the housing axis.
The sensor is «self-learning» and thanks to the advanced limens adjust system (ALAS), it works within a wide range of distances from the fabric, practically insensitive to its color and outside illumination.
The normal position is when the edge of the fabric lies directly opposite the transverse axis of the sensor, the fabric is located on the green LED side. Then the output current is 12 mA. When the plate edge is offset out of the sensor control field, the output current changes to 4 mA and moves to the reverse direction to 20 mA.