FB_BA_AC_ErcTSuACtrl

The template represents the supply air temperature control of an energy recovery system with the sequence controller Ctrl.

The sequence controller is enabled via the input variable bEn. If the control direction of the energy recovery system is indirect (heating mode) and the air conditioning system is in dehumidification mode bDehumf at the same time, energy recovery is blocked.

The sequence controllers are enabled for sequence control using the stSeqLink data and command structure. This is indicated by the variable bSeqActv.

Control direction

The control direction of the sequence controller Ctrl is selected based on a comparison of the outside temperature with the extract air temperature.

If the outside temperature is lower than the extract air temperature, the control direction of the sequence controller Ctrl is indirect (heating mode), see E_BA_Action.

If the outside temperature is higher than the extract air temperature, the control direction of the sequence controller Ctrl is direct (cooling mode), see E_BA_Action.

	The initialization of the template takes place within the method FB_Init.

Block diagram

Syntax

FUNCTION_BLOCK FB_BA_AC_ErcTSuACtrl EXTENDS FB_BA_View
VAR_INPUT
  bEn                 : BOOL;
  fSpTSuA             : REAL;
  fTSuA               : REAL;
  bSync               : BOOL;
  fSync               : REAL;
  bDehumf             : BOOL;
  fTExtA              : REAL;
  fTWth               : REAL;
END_VAR
VAR_OUTPUT
  fY                  : REAL;
  eAction             : E_BA_Action;
  bIsActive           : BOOL;
  bSeqActv            : BOOL;
END_VAR
VAR_IN_OUT
  stSeqLink           : ST_BA_SeqLink;
END_VAR
VAR_INPUT CONSTANT PERSISTENT
  {attribute 'parameterCategory' := 'Behaviour'}
  fHysActionOn        : REAL := 0.25;
  {attribute 'parameterCategory' := 'Behaviour'}
  fHysActionOff       : REAL := -0.25;
END_VAR
VAR_INPUT CONSTANT
  Ctrl                : FB_BA_SeqCtrl;
END_VAR
VAR
  HysAction           : FB_BA_Swi2P;
END_VAR

Inputs

Name	Type	Description
bEn	BOOL	Enable for the frequency controller Ctrl.
fSpTSuA	REAL	Setpoint of the supply air temperature.
fTSuA	REAL	Measured value of the supply air temperature.
bSync	BOOL	Pulse for synchronization of the sequence controller Ctrl.
fSync	REAL	Value for the synchronization of the sequence controller Ctrl.
bDehumf	BOOL	Indicates with a TRUE that the air conditioning system is in dehumidification mode.
fTExtA	REAL	Measured value extract air temperature
fTWth	REAL	Measured value weather temperature

Outputs

Name	Type	Description
fY	REAL	Control value output
eAction	E_BA_Action	The output of the control direction of the supply air controller Ctrl is required within an air conditioning system for the setpoint strategy.
bIsActive	BOOL	The sequence controller is the active one in the sequence control.
bSeqActv	BOOL	The sequence controller is implemented in the control sequence.

Inputs/outputs

Name	Type	Description
stSeqLink	ST_BA_SeqLink	The data and command structure is the link between the supply air temperature sequence controller Ctrl and the supply air temperature sequence controller TSeqLink of an air conditioning system.

Inputs CONSTANT PERSISTENT

Name	Type	Description
fHysActionOn	REAL	Upper switching point of the hysteresis HysAction to determine the control direction of the supply air controller Ctrl.
fHysActionOff	REAL	Lower switching point of the hysteresis HysAction to determine the control direction of the supply air controller Ctrl.

Inputs CONSTANT

Name	Type	Description
Ctrl	FB_BA_SeqCtrl	The supply air temperature sequence controller Ctrl is the core of this template. It is responsible for the supply air temperature control of the cooler. The sequence controller is also part of the supply air temperature sequence control of an air conditioning system, see sample FB_BA_AC_SeqT. The data exchange within this sequence control takes place via the data and command structure stSeqLink. The global variable E_BA_AC_SeqNumber_T.eEnergyRecovery gives the sequence controller its sequence number within the temperature sequence control.

Name

Type

Description

Ctrl

FB_BA_SeqCtrl

The supply air temperature sequence controller Ctrl is the core of this template. It is responsible for the supply air temperature control of the cooler.

The sequence controller is also part of the supply air temperature sequence control of an air conditioning system, see sample FB_BA_AC_SeqT. The data exchange within this sequence control takes place via the data and command structure stSeqLink.

The global variable E_BA_AC_SeqNumber_T.eEnergyRecovery gives the sequence controller its sequence number within the temperature sequence control.

Variables

Name	Type	Description
HysAction	FB_BA_Swi2P	The two-position switch determines the control direction of the sequence controller depending on the outside temperature fTWth and the extract air temperature fTExtA and the switching points of the hysteresis fHysActionOn/fHysActionOff. If the subtraction of the outside temperature fTWth and the extract air temperature fTExtA > fHysActionOn, then the output of the function block HysAction is TRUE. The control direction of the sequence controller Ctrl is therefore direct and energy recovery is in cooling mode. If the subtraction of the outside temperature fTWth and the extract air temperature fTExtA < fHysActionOff, then the output of the function block HysAction is FALSE. The control direction of the sequence controller Ctrl is therefore indirect and energy recovery is in heating mode.

Name

Type

Description

HysAction

FB_BA_Swi2P

The two-position switch determines the control direction of the sequence controller depending on the outside temperature fTWth and the extract air temperature fTExtA and the switching points of the hysteresis fHysActionOn/fHysActionOff.

If the subtraction of the outside temperature fTWth and the extract air temperature fTExtA > fHysActionOn, then the output of the function block HysAction is TRUE. The control direction of the sequence controller Ctrl is therefore direct and energy recovery is in cooling mode.

If the subtraction of the outside temperature fTWth and the extract air temperature fTExtA < fHysActionOff, then the output of the function block HysAction is FALSE. The control direction of the sequence controller Ctrl is therefore indirect and energy recovery is in heating mode.

Requirements

Development environment	Necessary function
TwinCAT from v3.1.4024.35	TF8040 \| TwinCAT Building Automation from V5.0.0.0