FB_CTRL_FLOW_TEMP_SETPOINT_GEN
This function block enables specification of a flow temperature depending on the external temperature.
Description:
The set value 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. An offset temperature can be used to implement night setback or precontrol.
Behaviour of the output value:
VAR_INPUT
VAR_INPUT
fAmbientTemperature : FLOAT;
fOffsetTemperature : FLOAT;
bLimitFlowTemp : BOOL;
END_VAR
fAmibientTemperature : Start of ramp generation.
fOffestTemperature : Starting value for the ramp.
bLimitFlowTemp : Finishing value for the ramp.
VAR_OUTPUT
VAR_OUTPUT
fOut : FLOAT;
eErrorId : E_CTRL_ERRORCODES;
bError : BOOL;
END_VAR
fOut : set value of the flow temperature.
eErrorId : Supplies the error number when the bError output is set.
bError : 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
stParams : Parameter structure of the ramp generator. This consists of the following elements:
TYPE
ST_CTRL_FLOW_TEMP_SETPOINT_GEN_PARAMS:
STRUCT
tTaskCycleTime : TIME; (* task cycle time [TIME]
*)
tCtrlCycleTime : TIME; (* controller cycle time [TIME]
*)
fForeRunTempMax : FLOAT;
fForeRunTempMin : FLOAT;
fAmbientTempMax : FLOAT;
fAmbientTempMin : FLOAT;
END_STRUCT
END_TYPE
tTaskCycleTime : 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 : 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.
fFlowTempMax : Maximum flow temperature (see diagram).
fFlowTempMin : Minimum flow temperature (see diagram).
fAmbientTempMax : Outdoor temperature for which the minimum flow temperature is specified.
fAmbientTempMin : Outdoor temperature for which the maximum flow temperature is specified.