The potentiometers on the module are voltage dividers connected to the supply voltage, with which a unique reference voltage can be set for each channel. This Vref is connected to the middle pin of the pin row. The outer pins of the pin row are wired to the two (IN+, IN-) inputs (figure). Using a jumper, you can switch the set reference voltage to the desired input, so 3 types of applications can be implemented:

Non-inverting comparator
Function 1 (Vref jumpered to the IN- input):
-When the voltage applied to the IN+ input exceeds the set comparison value (Vref, adjustable with a potentiometer), the relay is turned on.

Differential comparator
Function 2 (Vref not used, no jumper):
-If the voltage applied to the IN+ input is higher than IN-, the relay is turned on.

Inverting comparator
Function3 (Vref jumpered to IN+ input):
-When the voltage applied to the IN- input exceeds the set comparison value (Vref, adjustable with potentiometer) the relay turns off.

Hysteresis: approx. 30mV

Input:
- IN- : inverting input
- GND
- IN+ : non-inverting input