Convert 0-10 V to 4-20 mA using a resitor

 

It is extremely simple to measure 0-10 V analog signal from a sensor with a ACE PLC that will measure only current inputs.

If ACE current input accept a 0-20 mA signal, but may not accept a 0-10 V signal directly.

Basically, Ohms law is used to calculate a resistor value in order to convert the 0-10 V signal to a current.

For 0-20 mA, ACE have a internal 100 Ω shunt

A passive conversion can be performed by adding a resistor between the 0-10 V output of the transducer and the + terminal of the ACE mA input, taking advantage of the internal 100 Ω shunt.

Calculation:

We want: 0-10 V → 0-20 mA in loop.

Total resistance required for 20 mA : R_total = V / I = 10 V / 0.02 A = 500 Ω

Internal shunt ACE = 100 Ω. It contributes to the total resistance.

External resistance to be added : R_ext = R_total – R_shunt = 500 Ω – 100 Ω = 400 Ω