FB_CTRL_FLOW_TEMP_SETPOINT_GEN

FB_CTRL_FLOW_TEMP_SETPOINT_GEN 1:

This function block enables specification of a flow temperature depending on the outdoor temperature.

Description

The setpoint for the flow temperature (fOut) is determined from the ambient temperature (fAmbientTemperature). A straight line that can be moved via an offset (fOffsetTemperature) is used for this purpose. The slope is determined based on the specified ambient and flow temperature corners. A flag (bLimitFlowTemp) is used to specify whether or not the flow temperature is restricted to its limit values. The offset temperature can be used to realize a night setback or pre-control.

Behavior of the output value

FB_CTRL_FLOW_TEMP_SETPOINT_GEN 2:

VAR_INPUT

VAR_INPUT
    fAmbientTemperature  : FLOAT;
    fOffsetTemperature   : FLOAT;
    bLimitFlowTemp       : BOOL;
END_VAR

Name	Type	Description
fAmbient Temperature	FLOAT	Start of ramp generation
fOffset Temperature	FLOAT	Start value of the ramp
bLimitFlowTemp	BOOL	Target value of the ramp

VAR_OUTPUT

VAR_OUTPUT
    fOut      : FLOAT;
    eErrorId  : E_CTRL_ERRORCODES;
    bError    : BOOL;
END_VAR

Name	Type	Description
fOut	FLOAT	Setpoint of the flow temperature
eErrorId	E_CTRL_ERRORCODES	Supplies the error number when the output `bError` is set.
bError	BOOL	Becomes TRUE as soon as an error situation occurs.

VAR_IN_OUT

VAR_IN_OUT
    stParams    : ST_CTRL_FLOW_TEMP_SETPOINT_GEN_PARAMS;
END_VAR

Name	Type	Description
stParams	ST_CTRL_FLOW_TEMP_ SETPOINT_GEN_PARAMS	Parameter structure of the ramp generator

stParams consists of the following elements:

TYPE ST_CTRL_FLOW_TEMP_SETPOINT_GEN_PARAMS:
STRUCT
    tTaskCycleTime    : TIME;
    tCtrlCycleTime    : TIME;
    fForeRunTempMax   : FLOAT;
    fForeRunTempMin   : FLOAT;
    fAmbientTempMax   : FLOAT;
    fAmbientTempMin   : FLOAT;
END_STRUCT
END_TYPE

Name	Type	Description
tTaskCycleTime	TIME	Cycle time with which the function block is called. If the function block is called in every task cycle this corresponds to the task cycle time of the calling task.
tCtrlCycleTime	TIME	Cycle time with which the control loop is processed. This must be greater than or equal to the TaskCycleTime. The function block uses this input value to calculate internally whether the state and the output values have to be updated in the current cycle.
fForeRunTempMax	FLOAT	Maximum flow temperature (see diagram)
fForeRunTempMin	FLOAT	Minimum flow temperature (see diagram)
fAmbientTemp Max	FLOAT	outdoor temperature for which the minimum flow temperature is specified.
fAmbientTemp Min	FLOAT	outdoor temperature for which the maximum flow temperature is specified.