Differentiator_LinearFourPointApproximation (FB)¶

FUNCTION_BLOCK Differentiator_LinearFourPointApproximation EXTENDS Differentiator_Base

The function block uses recent values to approximate the derivation of a value with respect to time.

The last three values are recorded and used together with the current value and the elapsed time to estimate the derivation. The approximation is based on a linear approximation. This is extended to consider the last two and the current derivation. A weighted sum of these three derivatives is output.

Note

The sum of the weights should give 1.

By default, this function block mimics the behavior of Differentiator_BackwardDifference.

InOut:

Scope	Name	Type	Initial	Comment	Inherited from
Input	`xEnable`	`BOOL`		`TRUE`: Activates the defined operation `FALSE`: Aborts/resets the defined operation	LConC
Output	`xBusy`	`BOOL`		`TRUE`: Operation is running	LConC
Output	`xError`	`BOOL`		`TRUE`: Error condition reached	LConC
Input	`lrValue`	`LREAL`		Represents the current value that should be differentiated	Differentiator_Base
Input	`lrCycleInterval`	`LREAL`		Represents the elapsed time in [second]	Differentiator_Base
Output	`lrOutputValue`	`LREAL`		Represents the current derivative of the differentiator	Differentiator_Base
Output	`eErrorID`	ERROR	ERROR.NO_ERROR	The current error. Only valid if `xError` is `TRUE`.	Differentiator_Base
Input	`lrWeightD1`	`LREAL`	1
	`lrWeightD2`	`LREAL`	0
	`lrWeightD3`	`LREAL`	0

Properties:

CurrentDerivative, inherited from Differentiator_Base

OutputValue, inherited from Differentiator_Base

Methods:

CleanupAction

DoDifferentiation

StartAction

CyclicAction, inherited from Differentiator_Base

CyclicCall, inherited from Differentiator_Base

Reset, inherited from Differentiator_Base

ResetAction, inherited from Differentiator_Base

Structure: