When the value transformation is set to 4-20mA Scaling, the value of the raw data will be transformed by the 2 Point Formula. The 4-20mA Scaling selection is much like 2-Point Scaling, but assumes a 4-20mA transducer is installed. The channel must be an analog physical channel for this option to be available.
The X1 and X2 values are set to 4mA and 20mA by default for the transducer. By default Y1 is equal to 1 and Y2 is equal to 1000. If you prefer this transformation to be read as a percentage, change Y2 to equal 100.
The values of X1 and Y1 may be modified. Just confirm Y1 and Y2 correspond to the "real world" readings for those transducer values.