Smart Home Automation Forum

Hi, I want to know if I can use KC868-COLB Logical Controller to measure water level using the 2wire 4-20ma water sensor. Picture below.

KC868-COL/COLB/COLB-Mini support use analog sensor that 0-5V output, if you already have 4-20mA sensor. you can use a 250 Ohm resistance connect with signal input port and GND to convert.

To convert a mA analog input signal to voltage you need to attach a inline resistor. The size of your resistor will determine the output range of your voltage. 

Resistor Calculations are as follows:

Using ohms law V = R(I)  (Voltage = Resistance * Current)


If we were to scale a 4-20mA to 1-5V

For the 0 Value: .004 Amps * 250 ohms = 1 Volt

For the Max Value: .20 Amps * 250 ohms = 5 Volts