Determining the PLC Tools SIM-ALP2 0-20mA Engineering Units from 4-20mA scaling parameters

The SIM-ALP2's mA Engineering Units are based off of a low scale value at 0mA and a high scale value at 20mA.  To determine the 0mA value based off of a 4-20mA range use the following calculator or the formula below the calculator.

Milliamp mA Scaling Calculator

Engineering units at 4mA:

Engineering units at 20mA:

0mA value =


Formula to calculate mA scaling

  • Eu = Engineering Units
  • Eu0 = 0mA Engineering Units
  • Eu4 = 4mA Engineering Units
  • Eu20 = 20mA Engineering Units

Eu0= Eu4 - (Eu20-Eu4)/4


Eu0= (Eu4 *5 - Eu20)/4

Both do the same.

Example 1:  You need to simulate a pressure sensor that outputs 0-100psi.
Eu 4mA = 0, Eu 20mA = 100
Eu 0mA = -25

Example 2:  You need to simulate a length measurement sensor that outputs 100-300 inches.
Eu 4mA = 100, Eu 20mA = 300
Eu 0mA = 50

Once you have calculated the Eu 0mA, simply enter this in the Low Scale and enter Eu 20mA in the high scale.