3. Special software enhancement  curve and square root fitting (D122.AS.x.x.x)
The standard digital indicator D122 has a linear relation between measured and displayed current value  the option special software offers the possibility to program any monotone function between measured current and displayed value!
Non linear curve fitting:
The curve fitting software indicates the measure current in a nonlinear way. Consider an application of a fillinglevel meter for a spherical tank. The measure current is linear to the filling height of the liquid, but the function between the filling height and the volume is non linear. To get the correct quantity indication you require a list of points, which shows the connection between measure current and associated quantity inside the tank.
The curve fitting software of the D122.XS interpolates the curve between these points with a first (linear) or a second (square) order polynomial. The linear interpolation requires a list of 17 points  the square interpolation needs 33 points.
Square root fitting:
To program a square root function, e.g., to display the flow through an aperture, a special square root fitting feature is available. For this option, it is not necessary to enter a long list of points, but just a start and an end value (associated flow by 4 and by 20mA measure current). The indicator calculates automatically the selected points for interpolation. The measure error is less than 0,1 % full scale, if measure current is more than 5 mA.
To order the special software option use the following type code: D122.AS.x.x.x
