All four pins can be connected with wire.
I have attached the schematic, hopefully this helps.
The sensor has 3 main components on its circuit board. First, the sensor unit at the front of the module
which measures the area physically and sends an analog signal to the second unit, the amplifier. The amplifier amplifies the signal, according to the resistant value of the potentiometer, and sends the signal to
the analog output of the module. The third component is a comparator which switches the digital out and the LED if the signal falls under a
specific value. You can control the sensitivity by adjusting the potentiometer. The signal will be inverted; that means that if you measure a high value, it Please notice: is shown as a low voltage value at the analog output.
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