FB_BA_AC_ErcRot_01

FB_BA_AC_ErcRot_01 1:

The template represents the open-loop and closed-loop control of an energy recovery system with a rotary heat exchanger.

The main tasks of the template are:

The exhaust air minimum limiter TExhACtrl and the frost protection program IcePrtcRamp limit the control value of the temperature sequence controller TSuACtrl of the energy recovery system via a minimum selection to prevent the heat exchanger from icing up.

Principle diagram 01

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

FB_BA_AC_ErcRot_01 2:

Principle diagram 02

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

FB_BA_AC_ErcRot_01 3:
FB_BA_AC_ErcRot_01 4:

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

Block diagram

FB_BA_AC_ErcRot_01 5:

Syntax

FUNCTION_BLOCK FB_BA_AC_ErcRot_01 EXTENDS FB_BA_View
VAR_INPUT
  fSpTSuA           : REAL;
  fTSuA             : REAL;
  bSyncTSuACtrl     : BOOL;
  fSyncTSuACtrl     : REAL;
  bDehumf           : BOOL;
  fTExhA            : REAL;
  fTExtA            : REAL;
  fTWth             : REAL;
END_VAR
VAR_OUTPUT
  fPresentValue     : REAL;
  eAction           : E_BA_Action;
  bActiveSeqCtrl    : BOOL;
END_VAR
VAR_IN_OUT
  stTSeqLink        : ST_BA_SeqLink;
  stAggregate       : ST_BA_Aggregate;
END_VAR
VAR_INPUT CONSTANT
  TSuACtrl          : FB_BA_AC_PreHtrTSuACtrl;
  TExhACtrl         : FB_BA_PID_Sp;
  DiffPrssSwi       : FB_BA_SensorBinary;
  IcePrtcRamp       : FB_BA_RampLimitIncrease;
  Motor             : FB_BA_MotMdlt;
  PlantLock         : FB_BA_PlantLock;
  Aggregate         : FB_BA_Aggregate;
END_VAR
VAR
  bPrioSfty         : BOOL;
  bPrioCrit         : BOOL;
  PrioSwiVal        : FB_BA_PrioSwi_B04;
END_VAR

FB_BA_AC_ErcRot_01 6: Inputs

Name

Type

Description

fSpTSuA

REAL

Setpoint of the supply air temperature

fTSuA

REAL

Measured value of the supply air temperature

bSyncTSuACtrl

BOOL

Pulse for synchronization of the sequence controller TSuACtrl.

fSyncTSuACtrl

REAL

Value for the synchronization of the supply air sequence controller TSuACtrl.

bDehumf

BOOL

Input dehumidification mode active. This state has an effect on the sequence control in the supply air temperature control TSuACtrl template.

fTExhA

REAL

Measured value exhaust air temperature

fTExtA

REAL

Measured value extract air temperature

fTWth

REAL

Measured value weather temperature

FB_BA_AC_ErcRot_01 7: Outputs

Name

Type

Description

fPresentValue

REAL

Current value of the bypass damper system

eAction

E_BA_Action

The output of the control direction of the supply air controller TSuACtrl is required within an air conditioning system for the setpoint strategy.

bActiveSeqCtrl

BOOL

The sequence controller TSuACtrl is the active one in the sequence control.

FB_BA_AC_ErcRot_01 8: 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.

FB_BA_AC_ErcRot_01 9: Inputs CONSTANT

Name

Type

Description

TSuACtrl

FB_BA_AC_PreHtrTSuACtrl

The function block represents the supply air temperature control of energy recovery and is part of the temperature sequence control of an air conditioning system.

The control signal is forwarded to the analog control of damper Dmp via a minimum selection.

TExhACtrl

FB_BA_PID_Sp

The function block represents the exhaust air temperature control for the anti-icing of the plate heat exchanger.

DiffPrssSwi

FB_BA_SensorBinary

The binary input object represents a differential pressure monitor above the heat exchanger. This is used for anti-icing and activates the ramp function IcePrtcRamp.

IcePrtcRamp

FB_BA_RampLimitIncrease

The function block represents the anti-icing of the rotary heat exchanger using an increasing ramp function. This function is activated by means of the differential pressure monitor DiffPrssSwi.

Motor

FB_BA_MotMdlt

The function block is used to control a frequency converter. This then controls the motor of the rotary heat exchanger.

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 and the differential pressure control for anti-icing IcePrtcDiffPrssCtrl using the aggregate function block Aggregate and the global variable list Priority.

Requirements

Development environment

Necessary function

TwinCAT from v3.1.4024.35

TF8040 | TwinCAT Building Automation from V5.0.0.0