Control2P

Control2P (FB)

FUNCTION_BLOCK Control2P

Short description

2-point controller with actual value / setpoint / enable and adjustable switching hysteresis The action (inverted / direct) is also adjustable.

Representation

Interfaces

Inputs

Name	Data type	Value range	Initial value	Function
rX	REAL			Analog actual value
rW	REAL			Analog setpoint
xEn	BOOL			* FALSE: Controller locked * TRUE: Controller enabled

Outputs

Name	Data type	Value range	Initial value	Function
xY	BOOL			Digital output signal
rDiff	REAL			Control deviation ( rX - rW )
rOnAt	REAL			Absolute switch-on point ( rW + rSwitchOnPoint )
rOffAt	REAL			Absolute switch-off point ( rW + rSwitchOffPoint )

Setpoints / parameters

Name	Data type	Value range	Initial value	Function
rSwitchOffPoint	REAL		0.5	Switch-off point relative to setpoint rW
rSwitchOnPoint	REAL		-0.5	Switch-on point relative to setpoint rW
xOffCondition	BOOL		FALSE	State of the output xY at xEn = 0
xInitValue	BOOL		FALSE	State of the output xY after a restart
eAction	eControlMode		eControlMode.Inverted	Controller action (Inverted = heating, Direct = cooling)
eManModeB	eManBin		eManBin.Auto	Operating mode for the digital output signal xY

Function description

Enable input xEn

xEn	Control process	xY	rDiff	rOnAt	rOffAt	Notes
TRUE	TRUE	X	X	x	x	Enable of the control
FALSE	FALSE	xOffCondition ( if eManModeB = eManBin.Auto )	X	x	x	Locking of the control

Legend: X = any\

Digital output xY

The digital output xY is influenced by the enable input xEn, the control process and the manual override module.\

Control process	xEn	eManModeB	xY	Notes
FALSE	TRUE	eManBin.Auto	FALSE	Automatic operation - control process = FALSE
TRUE	TRUE	eManBin.Auto	TRUE	Automatic operation - control process = TRUE
X	FALSE	eManBin.Auto	xOffCondition	Automatic operation without enable
X	X	eManBin.ManOff	FALSE	Manual operation - Off
X	X	eManBin.ManOn	TRUE	Manual operation - On

Legend: X = any\

Control process

The controller can be operated in two different modes ( eAction = eControlMode.Inverted or eAction = eControlMode.Direct ). The following rules apply:\

eAction	Control
eControlMode.Inverted	rSwitchOnPoint < rSwitchOffPoint
eControlMode.Direct	rSwitchOnPoint > rSwitchOffPoint

If in operating mode eControlMode.Inverted the rSwitchOffPoint the rSwitchOnPoint, then the rSwitchOffPoint compared to the rSwitchOnPoint is increased by 0.1. If in operating mode eControlMode.Inverted the rSwitchOnPoint the rSwitchOffPoint, then the rSwitchOffPoint compared to the rSwitchOnPoint is reduced by 0.1. The output variables rDiff ( rX - rW ), absolute switch-on point rOnAt ( rW + rSwitchOnPoint ) and absolute switch-off point rOffAt ( rW + rSwitchOffPoint ) are available regardless of the enable input xEn always available.\

xEn	eAction	rDiff	xY	Notes
TRUE	eControlMode.Inverted	< rSwitchOnPoint	TRUE	Automatic operation - Inverted On
TRUE	eControlMode.Inverted	> rSwitchOffPoint	FALSE	Automatic operation - Inverted Off
TRUE	eControlMode.Direct	> rSwitchOnPoint	TRUE	Automatic operation - Direct On
TRUE	eControlMode.Direct	< rSwitchOffPoint	FALSE	Automatic operation - Direct Off

Legend: X = any In summary, the control process can alternatively be described as follows:\

xEn	eAction	rX	xY	Notes
TRUE	eControlMode.Inverted	< rOnAt	TRUE	Automatic operation - Inverted On
TRUE	eControlMode.Inverted	> rOffAt	FALSE	Automatic operation - Inverted Off
TRUE	eControlMode.Direct	> rOnAt	TRUE	Automatic operation - Direct On
TRUE	eControlMode.Direct	< rOffAt	FALSE	Automatic operation - Direct Off

Legend: X = don't care

CODESYS

InOut:

Scope	Name	Type	Initial
Input	rX	REAL
Input	rW	REAL
Input	xEn	BOOL
Input Const	rSwitchOffPoint	REAL	0.5
Input Const	rSwitchOnPoint	REAL	-0.5
Input Const	xOffCondition	BOOL	FALSE
Input Const	xInitValue	BOOL	FALSE
Input Const	eAction	eControlMode	eControlMode.Inverted
Input Const	eManModeB	eManBin	eManBin.Auto
Output	xY	BOOL
Output	rDiff	REAL
Output	rOnAt	REAL
Output	rOffAt	REAL