FB_BA_SpSupVis
Function block FB_BA_SpSupVisdient for processing and checking the lower and upper setpoint of a supply air humidity or temperature control.
Checks and limits for the setpoints
The function block limits the setpoints. The following two tables show which parameters are checked and what the response is in the event of an error.
Checking | Action | ||
---|---|---|---|
fSpLo > fSpHi | Last valid values of fSpLo and fSpHi are used. | ||
fSpMin >= fSpMax | Last valid values of fSpMin and fSpMax are used. | ||
fSpHi > fSpMax | fPrSpHi = fSpMax | ||
fSpLo < fSpMin | fPrSpLo = fSpMin | ||
Checking | bErr | Action | |
fSpMin >= fSpMax | TRUE | fSpErr = ((fSpMin + fSpMax) / 2) | |
fSpHi < fSpMin | |||
fSpLo > fSpMax |
The difference between the setpoints describes an energy-neutral zone. With supply air control, no heating or cooling would take place within the neutral zone.
The checked and possibly limited setpoints are output at the function block output as fPrSpHi und fPrSpLo (Present Setpoint).
Setpoint for heat recovery
For a heat recovery system, the setpoint fSpRcv is calculated either from the average of the upper and lower setpoints, fSpHi and fSpLo or as a function of the control direction of the heat recovery system.
The method is defined by the input variable bSlcnSpRcv:
b SlcnSpRcv | fSpRcv |
---|---|
TRUE | Average of fSpLo and fSpHi |
FALSE | Depends on control direction, defined through input bActRcv |
If the setpoint is defined depending on the control direction, the following applies:
bActRcv | Control direction | fSpRcv |
---|---|---|
TRUE | direct (cooling) | fSpHi |
FALSE | indirect (heating) | fSpLo |
Heat recovery
Inputs
VAR_INPUT
bEn : BOOL;
fSpHi : REAL;
fSpLo : REAL;
fSpMax : REAL;
fSpMin : REAL;
bActnRcv : BOOL;
bSlcnSpRcv : BOOL;
END_VAR
Name | Type | Description |
---|---|---|
bEn | BOOL | Function block enable. If bEn = FALSE, all output parameters are 0.0. |
fSpHi | REAL | Upper setpoint input value to be checked. |
fSpLo | REAL | Lower setpoint input value to be checked. |
fSpMax | REAL | Maximum setpoint |
fSpMin | REAL | Minimum setpoint. |
bActnRcv | BOOL | Direction of action of the downstream heat recovery. |
bSlcnSpRcv | BOOL | Setpoint selection of the downstream heat recovery system. |
Outputs
VAR_OUTPUT
fPrSpHi : REAL;
fPrSpLo : REAL;
fSpRcv : REAL;
bErr : BOOL;
sErrDescr : T_MAXSTRING;
END_VAR
Name | Type | Description |
---|---|---|
fPrSpHi | REAL | Output value for the upper setpoint. |
fPrSpLo | REAL | Output value for the lower setpoint. |
fSpRcv | REAL | Output value for the resulting heat recovery setpoint. |
bErr | BOOL | In case of a fault, e.g. if warning stages are active, this output is set to TRUE. |
sErrDescr | T_MAXSTRING | Contains the error description. |
Error description |
---|
01: Warning: The setpoints are not in a logical order: Either (fSpMin >= fSpMax) OR (fSpHi < fSpMin) OR (fSpLo > fSpMax) |
Requirements
Development environment | Required PLC library |
---|---|
TwinCAT from v3.1.4024.22 | Tc3_BA2 from v5.2.5.0 |