FB_BA_AC_TCasCtrl_02

The template is used for room temperature control by means of room-supply air cascade.

It consists of two master controllers for calculating the supply air temperature setpoints for the heater and cooler aggregates. Each of the two master controllers receives a separate setpoint. The setpoint of the master controller for the heating function is below the setpoint of the master controller for cooling. There is an energy-neutral zone between the two setpoints.

In addition, it determines the supply air temperature setpoint for energy recovery depending on its control direction.

The supply air temperature sequence control is enabled with the variable bOn by evaluating the receive block of the step sequence control Aggregate.

Principle diagram01

Principle diagram02

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

Block diagram

Syntax

FUNCTION_BLOCK FB_BA_AC_TCasCtrl_02 EXTENDS FB_BA_View
VAR_INPUT
  fSpRmHtg      : REAL;
  fSpRmCol      : REAL;
  fTRm          : REAL;
  eAction       : E_BA_Action := E_BA_Action.eDirect;
END_VAR
VAR_OUTPUT
  fSpHtg        : REAL;
  fSpCol        : REAL;
  fSpErc        : REAL;
  fMax          : REAL;
  fMin          : REAL;
  bOn           : BOOL;
END_VAR
VAR_IN_OUT
  stAggregate   : ST_BA_Aggregate;
END_VAR
VAR_INPUT CONSTANT
  SpHtg         : FB_BA_AV_Op;
  SpCol         : FB_BA_AV_Op;
  SpErc         : FB_BA_AV_Op;
  SelSpErc      : FB_BA_MV_Op;
  CtrlHtg       : FB_BA_Loop;
  CtrlCol       : FB_BA_Loop;
  LoopSync      : FB_BA_LoopSync;
  Aggregate     : FB_BA_Aggregate;
END_VAR
VAR
  PrioSwiVal    : FB_BA_PrioSwi_UDI04;
  MuxCmd        : FB_BA_MMUX_B04;
  MuxSpHtg      : FB_BA_MMUX_R04;
  MuxSpCol      : FB_BA_MMUX_R04;
  MuxSpErc      : FB_BA_MMUX_R04;
END_VAR

Inputs CONSTANT

Name	Type	Description
fSpRmHtg	REAL	Input variable for the setpoint room temperature Heating.
fSpRmCol	REAL	Input variable for the setpoint room temperature Cooling.
fTRm	REAL	Input variable to which the room temperature is applied. The room temperature is the control value of the PID master controller Ctrl. If no room temperature is available, the outlet air temperature of a ventilation system can be used as control value.
eAction	E_BA_Action	Input variable to which the control direction for the energy recovery is applied. The setpoint for the energy recovery is determined depending on the control direction.

Outputs

Name	Type	Description
fSpHtg	REAL	Calculated setpoint of the supply air temperature for the heater.
fSpCol	REAL	Calculated setpoint of the supply air temperature for the cooler.
fSpErc	REAL	Calculated setpoint of the supply air temperature. for energy recovery.
fMax	REAL	Upper value of the controller output limitation.
fMin	REAL	Lower value of the controller output limitation.
bOn	BOOL	The output shows the resulting result of the multiplexer MuxCmd. This is further processed within the ventilation system and is used to enable the supply air temperature sequence control.

Inputs/outputs

Name	Type	Description
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

Name	Type	Description
SpHtg	FB_BA_AV_Op	Analog value object for displaying the calculated room temperature setpoint heating.
SpCol	FB_BA_AV_Op	Analog value object for displaying the calculated room temperature setpoint cooling.
SpErc	FB_BA_AV_Op	Analog value object for displaying the calculated supply air temperature setpoint Energy recovery.
SelSpErc	FB_BA_MV_Op	The Multistate value object is used to select the strategy setpoint energy recovery. E_BA_AC_SelSpErc.eAction: = 1: Depends on the control direction, defined by input eErcAction. E_BA_AC_SelSpErc.eAverageHtgCol:= 2: Average of input variables fSpHtg and fSpCol.
CtrlHtg	FB_BA_Loop	The LOOP object serves as a master controller for a room temperature control by means of a room-supply air cascade. It provides the supply air temperature setpoint for heating.
CtrlCol	FB_BA_Loop	The LOOP object serves as a master controller for a room temperature control by means of a room-supply air cascade. It provides the supply air temperature setpoint for cooling.
LoopSync	FB_BA_LoopSync	The function block synchronizes the parameters for the two master controllers CtrlHtg/CtrlCol.
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
PrioSwiVal	FB_BA_PrioSwi_UDI04	The priority switch uses the command structure stCmd to determine the modulation command for the multiplexer MuxCmd.
MuxCmd	FB_BA_MMUX_B04	The multiplexer determines the current switching command from the modulation command of the priority switch PrioSwiVal. The resulting output is sent to the output bOn. The multiplexer defines the enabling conditions of the PID master controller Ctrl.
MuxSpHtg	FB_BA_MMUX_R04	The multiplexer defines the setpoint heating fSpHtg depending on the priority switch PrioSwiVal.
MuxSpCol	FB_BA_MMUX_R04	The multiplexer defines the cooling setpoint fSpCol depending on the priority switch PrioSwiVal.
MuxSpErc	FB_BA_MMUX_R04	The multiplexer defines the setpoint energy recovery fSpErc depending on the priority switch PrioSwiVal.

Requirements

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