FilterMonitoringB

FilterMonitoringB (FB)

FUNCTION_BLOCK FilterMonitoringB

Short description

Detection of filter contamination and generation of a fault message Typical application: Monitoring the contamination of an air filter with a differential pressure switch

Representation

Interfaces

Inputs

Name	Data type	Value range	Initial value	Function
xIn	BOOL			Input - differential pressure switch
xQuit	BOOL		FALSE	Reset - fault message

Outputs

Name	Data type	Value range	Initial value	Function
xAlarm	BOOL			Output - fault message
xPreAlarm	BOOL			Output - pre-alarm
tTimeToAlarm	TIME			Time duration until the fault message is triggered

Setpoints / Parameters

Name	Data type	Value range	Initial value	Function
udiControlTime	UDINT	1s … 3600s	300s	Waiting time
xControl	BOOL		TRUE	Enable monitoring

Function description

General

This function block is used to detect filter contamination by evaluating the input from the differential pressure switch xIn.

Enable monitoring xControl

The monitoring can be generally enabled ( = TRUE ) or disabled ( = FALSE ). If monitoring is not enabled, the output - fault message xAlarm is deactivated ( = FALSE ) and the time duration until the fault message is triggered tTimeToAlarm assumes the value 0s.

Output - pre-alarm xPreAlarm

The output - fault message xPreAlarm is activated ( xPreAlarm = TRUE ), if the condition 1 below is met. Condition 1: The input for the differential pressure switch xIn is in the state TRUE ( = filter contamination).

Output - fault message xAlarm

The output - fault message xAlarm is activated ( xAlarm = TRUE ), if the condition 1 below is met. Condition 1: The input for the differential pressure switch xIn remains in the state TRUE for at least the waiting time udiControlTime continuously ( = filter contamination ). At the same time the monitoring is generally enabled ( xControl = TRUE ). The output - fault message xAlarm is deactivated in the following cases ( xAlarm = FALSE ): Case 1: Condition 1 is not met and the reset of the fault message xQuit is active ( = TRUE ). Case 2: Condition 1 is not met and the enable of monitoring xControl is not active ( = FALSE ).

Time duration until the fault message is triggered tTimeToAlarm

At the output Time duration until the fault message is triggered tTimeToAlarm different values are displayed depending on the operating situation. Situation 1: Display of the remaining time until the fault message is triggered ( conditions: xIn = TRUE, xControl = TRUE ) Situation 2: If Situation 1 does not apply, the value 0.0 is output continuously.

CODESYS

InOut:

Scope	Name	Type	Initial
Input	xIn	BOOL
Input	xQuit	BOOL	FALSE
Input Const	udiControlTime	UDINT	300
Input Const	xControl	BOOL	TRUE
Output	xAlarm	BOOL
Output	xPreAlarm	BOOL
Output	tTimeToAlarm	TIME