FB_BA_Chrct04

The function block FB_BA_Chrct04 represents a linear interpolation with 4 interpolation points and can be used to generate a characteristic curve. The characteristic curve is determined by the interpolation points [rX1/rY1] to [rX4/rY4]. If the input variable bLmt is TRUE, rY is limited by rY01 and rY04. If bLmt is FALSE, rY is not limited.

Error handling

The input values for rX[n+1] must always be at least 0.0000001 greater than the values for rX[n].
In the event of an error the variable sErrDescr indicates that at one point of the characteristic curve the values are not monotonically increasing.

VAR_INPUT

rX    : REAL;
rX01  : REAL;
rX02  : REAL;
rX03  : REAL;
rX04  : REAL;
rY01  : REAL;
rY02  : REAL;
rY03  : REAL;
rY04  : REAL;
bLmt  : BOOL;

rX: Input value of the characteristic curve.

rX01: X-value for interpolation point P1.

rX02: X-value for interpolation point P2.

rX03: X-value for interpolation point P3.

rX04: X-value for interpolation point P4.

rY01: Y-value for interpolation point P1.

rY02: Y-value for interpolation point P2.

rY03: Y-value for interpolation point P3.

rY04: Y-value for interpolation point P4.

bLmt: Limit for the output value rY.

VAR_OUTPUT

rY        : REAL;
bErr      : BOOL;
sErrDescr : T_MAXSTRING;

rY: Calculated output value of the characteristic curve.

bErr: This output is switched to TRUE if the parameters entered are erroneous.

sErrDescr: Contains the error description.

Requirements