Control2P (FB)

FUNCTION_BLOCK Control2P

Short Descritpion

2-point controller with actual value / set point / enable and configurable switching hysteresis

The direction of the action (inverted / direct) is also adjustable.

Portrayal

Interfaces

Inputs

Name	Datatype	Range	Init-Value	Function
rX	REAL			Analog actual value
rW	REAL			Analog setpoint
xEn	BOOL			FALSE: Disable controller TRUE: Enable Controller

Outputs

Name	Datatype	Range	Init-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	Datatype	Range	Init-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	Status of output xY at xEn = 0
xInitValue	BOOL		FALSE	Status of output xY after a restart
eAction	eControlMode		eControlMode.Inverted	Direction of action of the controller (inverted = heating, direct = cooling)
eManModeB	eManBin		eManBin.Auto	Operating mode for the digital output signal xY

Functional Description

Enabling Input xEn

xEn	Controlling process	xY	rDiff	rOnAt	rOffAt	Notes
TRUE	TRUE	X	X	x	x	Enabling the control
FALSE	FALSE	xOffCondition ( falls eManModeB = eManBin.Auto )	X	x	x	Disabling the control

Legend: X = any

Digital output xY

The digital output xY is influenced by the enable input xEN, the controlling process, and the manual override module.

Controlling process	xEn	eManModeB	xY	Notes
FALSE	TRUE	eManBin.Auto	FALSE	Automatic operation - controlling process = FALSE
TRUE	TRUE	eManBin.Auto	TRUE	Automatic operation - controlling process = TRUE
X	FALSE	eManBin.Auto	xOffCondition	Automatic operation without enabling
X	X	eManBin.ManOff	FALSE	Manual operation - Off
X	X	eManBin.ManOn	TRUE	Manual operation - On

Legend: X = any

Controlling process

The controller can be operated in two different operating modes (eAction = eContollerOp.Invertiert or eAction = eControllerOp.

The following rules apply:

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

If in the eControlMode.Inverted operating mode, the rSwitchOffPoint falls below the rSwitchOnPoint, the rSwitchOffPoint is raised with respect to

rSwitchOnPoint by 0.1.

If in the ControlMode.Inverted operating mode,the rSwitchOnPoint falls below the rSwitchOffPoint, the rSwitchOffPoint is reduced with respect to the

** rSwitchOnPoint** by 0.1.

The rDiff (rX - rW) output variables , rOnAt (rW + rSwitchOnPoint) absolute switch-on point and rOffAt (rW* + rSwitchOffPoint) absolute switch-off point

are always available irrespective of the xEn enable input.

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 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 = any

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	02.2017	1.0	Initial version
Documentation	Jochen Reu	10.2017	1.0	Initial version

Codesys

InOut:

Scope	Name	Type	Initial	Comment
Input	rX	REAL		Analog actual value
	rW	REAL		Analog setpoint
	xEn	BOOL		Enable the Controller
	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	Status of output xY at xEn = 0
	xInitValue	BOOL	FALSE	Status of output xY after a restart
	eAction	eControlMode	eControlMode.Inverted	Direction of action of the controller (inverted = heating, direct = cooling)
	eManModeB	eManBin	eManBin.Auto	Operating mode for the digital output signal xY
Output	xY	BOOL		Binary control signal for control
	rDiff	REAL		Control deviation Xw
	rOnAt	REAL		Switch-on point at
	rOffAt	REAL		Switch-off point at