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8 Configuration - setup only
8.9 Customized linearization
The user can create an individual linearization characteristic line for the analog input with the customer-
specific linearization. Two procedures are available for this (type of linearization): formula or grid points
(value pairs).
The text entered under "designation" is not used at another point in the setup program, but serves merely
as text in the sense of a brief description.
Formula
Linearization is specified using a formula with five coefficients (4th order polynomial).
Polynomial: y = X4*x
4
+ X3*x
3
+ X2*x
2
+ X1*x + X0
"Display graphic" button (displaying linearization on a graphic):
Use this button to create a graphic of the linearization.
The graphic includes the characteristic lines for both types of linearization where applicable, namely the
formula and the grid points (table).
The display range for the graphic is initially determined by the "measuring range start" and "measuring
range end" values (y values); it can be temporarily changed in the display by entering different x values.
Grid points
Linearization is specified by entering up to 40 grid points (pairs of values X,Y). The value X stands for
the physically measured value (resistance in Ω or voltage in mV) for a RTD temperature probe or ther-
mocouple. With the other signal types, the input variable is scaled to 0 to 100% (for voltage/current signal
of measuring range, for resistance/potentiometer of resistance Rx, for resistance transmitter of overall
resistance). The value Y is the linearized value (e.g., temperature in °C).
button (calculating the polynomial using the grid points):
After entering the value pairs, use this button to calculate a polynomial that describes the progression of
the linearization characteristic line.
The calculated coefficients are incorporated into the formula. The characteristic lines for both types of
linearization then correspond to each other.
If the x values do not increase in a straight line, the linearization is not applied. In this case, it is impos-
sible to display the graphic or calculate the polynomial.
"Display graphic" button (displaying linearization on a graphic):
Use this button to create a graphic of the linearization.
Parameter Selection/text/value Description
Measuring range start -1999 to 9999 (0) Start value of the y axis (linearized value)
Measuring range end -1999 to 9999 (100) End value of the y axis (linearized value)
X0 -1999 to 9999 (0) Absolute component of the polynomial (point of in-
tersection with the y axis)
X1 -1999 to 9999 (0) Coefficient of the linear component (x)
X2 -1999 to 9999 (0) Coefficient of the quadratic component (x
2
)
X3 -1999 to 9999 (0) Coefficient of the cubic component (x
3
)
X4 -1999 to 9999 (0) Coefficient of the quartic component (x
4
)
Parameter Selection/text/value Description
Measured value (X) -1999 to 9999 (0) Value of the relevant grid point on the x axis
Linearized value (Y) -1999 to 9999 (0) Value of the relevant grid point on the y axis
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