DampingT1 (FB)

FUNCTION_BLOCK DampingT1

Functional Description

Timing filtering of an analog input signal

Typical application: filtering of a raw sensor value

Portrayal

Interfaces

Inputs

Name	Datatype	Range	Init-Value	Function
rIn	REAL			Analog value input

Outputs

Name	Datatype	Range	Init-Value	Function
rOut	REAL			Filtered analog value output

Setpoints / Parameters

Name	Datatype	Range	Init-Value	Function
tTimeConstant	TIME	5s...	T#10s	Filter - Time constant
rInitValue	REAL		100	Init-Value
eInitial	eInit		eInit.InputValue	Selection of the initialization value
tInitDelay	TIME		T#5s	Start delay - Initialization

Functional Description

General

The analog input signal rIn is checked for value changes at the sampling time interval (here: 1s, fixed setting).

If the actual value at input rIn at time t differs from the value at output rOut at time t-sampling time, the actual output value rOut at time t is calculated according to the following algorithm:

rOut = rOut*(t-sampling time) + ( ( *rIn - rOut*(t-sampling time) ) * ( sampling time / **tTimeConstant* ) )

Legend:

rOut = filtered analog value output at time point t

rOut (t-sampling time) = filtered analog value output at the time point t-sampling time

rIn = Analog value input at time point t

sampling time = 1s

tTimeConstant = Filter - time constant

t = current time

Rules for setting the filters - time constant tTimeConstant

tTimeConstant > ( sampling time * 5 )

tTimeConstant = 0: rOut = *rIn

Type of initialization eInitial

This setpoint / parameter defines the type of initialization of the analog value input rIn.

The initialization is performed once after each CPU restart.

The following options are possible:

Art	Initialization value	Notes
eInit.InitValue	rInitValue	Configurable initial value
eInit.InputValue	rIn	Input value
eInit.InputValueDelayed	rIn	Delayed input value

The initialization is performed independent of this if the setpoint / parameter tTimeConstant has the value T#0s.

Visualization

Information

Element	Authors	Date	Version	Notes
Function	Adam Bartod	04.2016	1.0	Initial version
Programming	Adam Bartod	04.2016	1.0	Initial version
Test	Jochen Reu	10.2017	1.0	Initial version
Documentation	Jochen Reu	10.2017	1.0	Initial version

Codesys

InOut:

Scope	Name	Type	Initial	Comment
Input	rIn	REAL		Analog value input
	tTimeConstant	TIME	TIME#10s0ms	Filter - Time constant
	rInitValue	REAL	100	Init-Value
	eInitial	eInit	eInit.InputValue	Selection of the initialization value
	tInitDelay	TIME	TIME#5s0ms	Start delay - Initialization
Output	rOut	REAL		Filtered analog value output