FB_FTR_ActualValue

The function block allows a measured input value to be checked for plausibility and filtered.

If the difference between two sampling values in sequence is larger than the specified window, fDeltaMax, then the current input value is suppressed for a maximum of three cycles. During this time the output value is linearly extrapolated from the previous input values. If the specified window is exceeded for more than three cycles, the output will again follow the input value.

Variable n is incremented if |x_k - x_k-1| > fDeltaMax.

The filter specification is transferred with the structure ST_FTR_ ActualValue.

Syntax

Declaration:

fbFilter : FB_FTR_ActualValue(stConfig := ...)

Definition:

FUNCTION_BLOCK FB_FTR_ActualValue
VAR_INPUT
    stConfig        : ST_FTR_ActualValue;
END_VAR
VAR_OUTPUT
    bError          : BOOL;
    bConfigured     : BOOL;
    ipResultMessage : I_TCMessage;
END_VAR

Inputs

Name	Type	Description
stConfig	ST_FTR_ActualValue	Structure for configuring the filter behavior

Outputs

Name	Type	Description
bError	BOOL	TRUE, if an error occurs.
bConfigured	BOOL	TRUE if the configuration was successful.
ipResultMessage	I_TCMessage	Interface that provides properties and methods for message handling.

Methods

Name	Definition location	Description
Configure()	Local	Loads a new (or initial) configuration structure.
Call()	Local	Calculates the output signal for a given input signal and filter configuration.
Reset()	Local	Resets internal states.
GetFilterActive()	Local	Indicates which elements of the input signal have been changed.
GetFilterActiveTimestamps()	Local	Shows when the filter was last active.

Properties

Name	Type	Access	Definition location	Initial value	Description
bTraceLevelDefault	BOOL	Get, Set	Local	TRUE	TRUE if eTraceLevel = Critical.
eTraceLevel	TcEventSeverity	Get, Set	Local	Critical	Severity of an event.
nTimestamp	UINT	Set	Local	0	Timestamp of the oldest input value of the next Call().
tSamplePeriod	LTIME	Set	Local	0	Time difference between two input values.

Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT v3.1.4022.25	PC or CX (x64, x86)	Tc3_Filter

Further Information