The UTIL.LIB Library • 337

Mathematical help functions

14.4 Mathematical help functions

14.4.1DERIVATIVE

This function block approximately determines the local derivation.

The function value is delivered as a REAL variable by using IN. TM contains the time which has passed in msec in a DWORD and the input of RESET of the type BOOL allows the function block to start anew through the delivery of the value TRUE.

The output OUT is of the type REAL.

In order to obtain the best possible result, DERIVATIVE approximates using the last four values, in order to hold errors which are produced by inaccuracies in the input parameters as low as possible.

Block in FBD:

14.4.2INTEGRAL

This function block approximately determines the integral of the function.

In an analogue fashion to DERIVATIVE, the function value is delivered as a REAL variable by using IN. TM contains the time which has passed in msec in a DWORD and the input of RESET of the type BOOL allows the function block to start anew with the value TRUE.

WAGO-I/O-SYSTEM 759 WAGO-I/O-PRO 32

338 • The UTIL.LIB Library

Mathematical help functions

The output OUT is of the type REAL.

The integral is approximated by two step functions. The average of these is delivered as the approximated integral.

Block in FBD: Example: Integration of a linear function:

14.4.3STATISTICS_INT

This function block calculates some standard statistical values:

The input IN is of the type INT. All values are initialised anew when the

BOOLean input RESET is TRUE.

The output MN contains the minimum, MX of the maximum value from IN. AVG describes the average, that is the expected value of IN. All three outputs are of the type INT.

Block in FBD:

14.4.4STATISTICS_REAL

This function block corresponds to STATISTICS_INT, except that the input IN is of the type REAL like the outputs MN, MX, AVG.

14.4.5VARIANCE

VARIANCE calculates the variance of the entered values.

The input IN is of the type REAL, RESET is of the type BOOL and the output OUT is again of the type REAL.

This block calculates the variance of the inputted values. VARIANCE can be reset with RESET=TRUE.

The standard deviation can easily be calculated as the square root of the

VARIANCE.

WAGO-I/O-SYSTEM 759 WAGO-I/O-PRO 32