I have a question. Is it a good way to measuring 4-20mA with differential ADC?
Assume that we have a ADC with 2 single ended inputs or 1 differential input. Input A+ is the first input and input A- is the last input. If we connect a 4-20mA sensor to A+ and a resistor between A+ and GND so we get a pressure drop just to convert mA to Voltage.
Then on A- we do voltage dividing so we get the same input voltage as the sensor gives us at 4mA. Assume that we get 0.2V at 4mA from the sensor. When A+ and A- have 0.2V, then our ADC value is 0. When we have 20mA from the sensor, then our ADC shows maximum value.
Is this a good strategy? Or should I use single ended ADC instead and accept that my ADC value will be a little bit higher because 4mA causes voltage input? So instead of the start ADC value will be 0, then we have e.g about 500 ADC value at start.