FB_BA_AC_ColT_01

The template represents the open-loop and closed-loop control of a cold water air cooler without dehumidification control.

The main tasks of the template are:

Control of the supply air temperature, see TSuACtrl
Enable the cooler pump, see Pu
Control of the cooler valve, see Vlv
Collecting and evaluating safety-relevant faults using the PlantLock
To be part of the step sequence control of an air conditioning system, see Aggregates

Principle diagram 01

The diagram shows the intended use of the template with the plant elements involved.

Principle diagram 02

The diagram shows the integration of the template within a plant.

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

Block diagram

Syntax

FUNCTION_BLOCK FB_BA_AC_ColT_01 EXTENDS FB_BA_View
VAR_INPUT
  fSpTSuA           : REAL;
  fTSuA             : REAL;
  bSyncTSuACtrl     : BOOL;
  fSyncTSuACtrl     : REAL;
END_VAR
VAR_OUTPUT
  bCmd              : BOOL;
  fPresentValue     : REAL;
  bActiveSeqCtrl    : BOOL;
END_VAR
VAR_IN_OUT
  stTSeqLink        : ST_BA_SeqLink;
  stAggregate       : ST_BA_Aggregate;
END_VAR
VAR_INPUT CONSTANT PERSISTENT
  {attribute 'parameterCategory' := 'Behaviour'}
  fHysPuOn          : REAL := 5.0;
  {attribute 'parameterCategory' := 'Behaviour'}
  fHysPuOff         : REAL := 1.0;
END_VAR
VAR_INPUT CONSTANT
  TFl               : FB_BA_SensorAnalog;
  TRt               : FB_BA_SensorAnalog;
  TSuACtrl          : FB_BA_AC_ColTSuACtrl;
  Vlv               : FB_BA_Vlv;
  Pu                : FB_BA_Pu1st;
  PlantLock         : FB_BA_PlantLock;
  Aggregate         : FB_BA_Aggregate;
END_VAR
VAR
  bPrioSfty         : BOOL;
  bPrioCrit         : BOOL;
  PrioSwiVal        : FB_BA_PrioSwi_B04;
  HysPu             : FB_BA_Swi2P;
END_VAR

Inputs

Name	Type	Description
fSpTSuA	REAL	Setpoint of the supply air temperature
fTSuA	REAL	Measured value of the supply air temperature
bSyncTSuACtrl	BOOL	Input for synchronization of the supply air sequence controller in the function block TSuACtrl.
fSyncTSuACtrl	REAL	Synchronization value for the supply air sequence controller in the function block TSuACtrl.

Outputs

Name	Type	Description
bCmd	BOOL	Current switching status of the single-stage pump
fPresentValue	REAL	Current value of the cooler valve
bActiveSeqCtrl	BOOL	Indicates that the sequence controller of the cooler is the active one in the sequence control.

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.
stAggregate	ST_BA_Aggregate	Bidirectional aggregate structure via which the enables and switching values are transmitted to the evaluation function block of the step sequence control Aggregate. The aggregate structure transmits the recorded feedback signals up and down to the central plant control.

Inputs CONSTANT PERSISTENT

Name	Type	Description
fHysPuOn	REAL	Upper switching point of the hysteresis to switch on the pump.
fHysPuOff	REAL	Lower switching point of the hysteresis to switch off the pump.

Inputs CONSTANT

Name	Type	Description
TFl	FB_BA_SensorAnalog	The function block represents the flow temperature sensor.
TRt	FB_BA_SensorAnalog	The function block represents the return temperature sensor.
TSuACtrl	FB_BA_AC_ColTSuACtrl	The function block represents the supply air temperature control of the cooler and is part of the temperature sequence control of an air conditioning system. The control signal is forwarded to the valve Vlv.
Vlv	FB_BA_Vlv	The function block represents the valve.
Pu	FB_BA_Pu1st	The function block represents the cooler pump.
PlantLock	FB_BA_PlantLock	When the function block is called, the relevant faults of the event-enabled objects are collected and output at this and lower levels of the template. These relevant faults cause specific switching actions via the variables bPrioSfty and bPrioCrit in the template. The parameterization of the lock priority of the event-enabled objects can be found in the FB_init of this template.
Aggregates	FB_BA_Aggregate	The aggregate function block represents a receive block of a step sequence controller. Within the function block, the aggregate structure stAggregate is evaluated and integrated into the template using the inputs and outputs.

Variables

Name	Type	Description
bPrioSfty	BOOL	The variable is an evaluation of the "Safety" lock priority of the event-enabled objects in the project structure and causes targeted switching actions in the template when a relevant fault is triggered.
bPrioCrit	BOOL	The variable is an evaluation of the "Critical" lock priority of the event-enabled objects in the project structure and causes targeted switching actions in the template when a relevant fault is triggered.
PrioSwiVal	FB_BA_PrioSwi_B04	The priority switch PrioSwiVal determines the switching conditions and enables for the supply air temperature control TSuACtrl using the aggregate function block Aggregate and the global variable list Priority.
HysPu	FB_BA_Swi2P	The two-position switch HysPu switches the pump Pu on and off depending on the valve position fPresentValue and the switching points of the hysteresis fHysPuOn/fHysPuOff.

Requirements

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