FB_BA_AnalogInput

The FB_BA_AnalogInput function block is used to acquire and scale analog input signals.

The raw value nRawValue is converted into a physical value by linear interpolation with 2 interpolation points.

Within the parameters, it is possible to activate upper (stHighLimit) and lower (stLowLimit) limit value monitoring of the output signal fPresentValue.

In addition, the function block can be provided with a PT-1 filter to avoid strong fluctuations by the input signal nRawValue. The filter is activated by adjusting the filter constants nDampingConstant > 0.

Syntax

FUNCTION_BLOCK FB_BA_AnalogInput
VAR_INPUT
  nRawValue            : INT;
END_VAR
VAR_INPUT CONSTANT PERSISTENT
  {region 'Variable Parameters'}
    {attribute 'parameterCategory':='Hardware'}
    stScale            : ST_BA_ScaleIntToReal := (nX01 := 0,nX02 := 32767,nY01 := -20,nY02 := 60);
    {attribute 'parameterCategory':='Hardware'}
    fOffset            : REAL;
    {attribute 'parameterCategory':='EventConfig'}
    stHighLimit        : ST_BA_LimitParameter := (nTimeToAbnormal := 1, nTimeToNormal := 1);
    {attribute 'parameterCategory':='EventConfig'}
    stLowLimit         : ST_BA_LimitParameter := (nTimeToAbnormal := 1, nTimeToNormal := 1);
    {attribute 'parameterCategory':='Value'}
    nDampingConstant   : UDINT;
  {endregion}
END_VAR
VAR_OUTPUT
  fPresentValue        : REAL;    
  bHighLimit           : BOOL;
  bLowLimit            : BOOL;
END_VAR

Inputs

Name	Type	Description
nRawValue	INT	Measured raw value.

Inputs CONSTANT PERSISTENT

Name	Type	Description
stScale	ST_BA_ScaleIntToReal	The structure contains the interpolation points for linear interpolation.
fOffset	REAL	The offset can be used to adjust the scaled output value fPresentValue.
stHighLimit	ST_BA_LimitParameter	Data and command structure for upper limit value monitoring.
stLowLimit	ST_BA_LimitParameter	Data and command structure for lower limit value monitoring.
nDampingConstant	UDINT	To avoid strong fluctuations and jumps in the input signal, the function block is provided with a PT1 filter. This filter is activated by setting the filter constant nDampingConstant to greater than 0.

Outputs

Name	Type	Description
fPresentValue	REAL	Scaled output value.
bHighLimit	BOOL	The upper limit monitoring is active.
bLowLimit	BOOL	The lower limit monitoring is active.

Prerequisites

Development environment	Required PLC library
TwinCAT from v3.1.4024.62	Tc3_BA2 from v5.5.14.0