You can use the Signal Characterizer function block as a curve fitting function. For example, you can scale a 4 to 20 mA input signal to a 0 to 100% output value using the block. You can also use the block to convert measurements from a split-range or other nonlinear device or from a dual-temperature control device used for both heating and cooling.
You can use the Signal Characterizer function block to alter the relationship of a PID function block output to valve position and gain more linear control over a critical region.