AbsA

AbsA (FB)

FUNCTION_BLOCK AbsA

Short description

Anti-blocking protection for an analog signal

Representation

Interfaces

Inputs

Name	Data type	Value range	Initial value	Function
rPosFb	REAL			Position feedback

Outputs

Name	Data type	Value range	Initial value	Function
rOut	REAL			Analog - output
xAbsOn	BOOL			Indicator - anti-blocking process
dtAbsLastOn	DATE_AND_TIME			Start date/time of the last anti-blocking process

Setpoints / parameters

Name	Data type	Value range	Initial value	Function
rMinChange	REAL		10.0	Minimum position change
tTime	TIME		180s	Duration of the anti-blocking process
eDay	eDoW		eDow.Monday	Weekday of the anti-blocking process
todStartTime	TOD		08:00:00 hrs	Start time of the anti-blocking process
rMinLimit	REAL		0	Lower limit for the analog output rOut
rMaxLimit	REAL		100	Upper limit for the analog output rOut

Function description

General

This function block is used to monitor the position feedback rPosFb for activity. The inspection period covers 168 hours each time ( = 1 week ). The position feedback rPosFb is considered active if its value has changed during the inspection period by an amount greater than the minimum position change rMinChange The anti-blocking process is thereby prevented ( = anti-blocking process not active ), and the inspection period starts again. If no activity is detected during the inspection period, the anti-blocking process is triggered with the duration tTime on the weekday eDay at the time todStartTime Triggered. ( = anti-blocking process active ). At the same time the inspection period restarts. During the anti-blocking process, different signals are output on the analog output rOut depending on the current value of the position feedback rPosFb at the start of the anti-blocking process. Condition 1: rPosFb > 51% of the upper limit for the analog output rOut: &#xNAN;rOut = rMinLimit Condition 2: rPosFb <= 51% of the upper limit for the analog output rOut: &#xNAN;rOut = rMaxLimit When the anti-blocking process is not active, the analog output rOut outputs the value 0.0. The initial triggering of the anti-blocking process may be delayed depending on the relevant settings ( weekday eDay and todStartTime ). For example: inspection period ends on Tuesday morning, triggering of the anti-blocking process only the following Monday). At the output dtAbsLastOn the start date and start time of the last anti-blocking process are available. \

Prerequisite for using the AbsA function block

For correct operation, the use of the TimeRead2 function block is required.\

Indicator - anti-blocking process xAbsOn

This output is used to indicate an active anti-blocking process ( xAbsOn = TRUE ).\

Setpoint / parameter eDay

The anti-blocking function can be generally disabled by setting eDay = eDow.Inactive.\

Setpoint / parameter tTime

The anti-blocking function can be generally disabled by setting tTime = 0s can be generally disabled.

CODESYS

InOut:

Scope	Name	Type	Initial
Input	rPosFb	REAL
Input Const	rMinChange	REAL	10
Input Const	tTime	TIME	TIME#3m0s0ms
Input Const	eDay	eDoW	eDow.Monday
Input Const	todStartTime	TOD	TIME_OF_DAY#8:0
Input Const	rMinLimit	REAL	0
Input Const	rMaxLimit	REAL	100
Output	rOut	REAL
Output	xAbsOn	BOOL
Output	dtAbsLastOn	DT