FC_CSplineFromFile

 

FC_CSplineFromFile - General Information

Overview

Task

Calculate the coefficients for a curve from a supporting point table.

Description

The function calculates the coefficients for a cubic spline interpolation in the controller from a cam point table. Cubic spline interpolation provides jerk-free acceleration regardless of the number of cam points. A cam point just consists of a Y value; the X values are assumed equidistant and calculated by the system.

The cam points and some extra information are transferred via i_sInFile, which has to be created beforehand.

The output of the coefficients is carried out through FC_CSplineFromFile in the i_sOutFile.

The "Infile.dat" file is created using the IEC file services. It contains:

The data to be interpolated can be provided in a binary or an ASCII file. If the input is to come from an ASCII file, it must have the "*.asc" extension. The other files are interpreted as binary files.

oVersion

The version of the cam point file must be 0 at this time.

oType in the input file

You can select from three spline types:

oSpline type = 0

Natural spline (second derivatives in boundary points = 0)

oSpline type = 1

Derivatives in boundary points are preset (such as FC_CSplineFromFile())

oSpline type = 2

Periodic spline

oLeft boundary slope

The value of the derivative at the start point. This value is ignored for spline types 0 (natural spline) and 2 (periodic spline).

oRight boundary slope

The value of the derivative at the end point. This value is ignored for spline types 0 (natural spline) and 2 (periodic spline).

oCam points

Values must be normalized to –1.0 ... +1.0. The number of cam points may vary from 3 to 10,000 values.

Interface

Return Value

Examples

FC_CSplineFromFile( i_sInFile:='Kurve1', i_sOutFile:='Kurve1' );

FC_CSplineFromFile( i_sInFile:='Kurve1.asc', i_sOutFile:='Kurve1' );