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# CascadeExtractSupplyAirX2Setpt
## `CascadeExtractSupplyAirX2Setpt` (FB)
FUNCTION\_BLOCK CascadeExtractSupplyAirX2Setpt
### Short description
> Generation of two supply air setpoint temperatures using two cascade controllers (PI controllers)\
> Additional functions: Limitation of the supply air setpoint temperatures\
> Typical application: Supply air temperature control in an air-handling unit with active cooling
### Representation
### Functional description
#### General
This function block corresponds to the block ‘CascadeExtractSupplyAirTemperature’, which is extended here by an additional cascade controller for generating a separate supply air setpoint temperature for the cooler in active cooling mode.
CascadeExtractSupplyAirTemperature
This function block is used to generate the supply air setpoint temperature of a ventilation system from
1. Current setpoint temperature (exhaust air or room temperature) in °C
\
2\) Current actual temperature (exhaust air or room temperature) in °C\
\
taking into account the relative (rMinSUPTemp or rMaxSUPTemp) and absolute (rMinSUP or rMaxSUP) limits.\
In addition, when forming the supply air setpoint, the special operating modes ‘Rapid heating’ and ‘Free night cooling’ are taken into account.\
The supply air setpoint is formed with a delay (tDelayControl) after the controller is enabled / disabled (xEn = TRUE).\
\
The cascade controller is enabled if the following conditions described below are all met at the same time:\
\
1\) The special operating mode Rapid heating is disabled (xFastHeatEn = FALSE).\
\
2\) The special operating mode Free night cooling is disabled (xFNCEn = FALSE).\
\
3\) The current actual temperature rActTemp does not violate its absolute limit values (+5.0 - +50.0 °C).\
\
4\) Control is enabled (xEn = TRUE) and the switch-on delay (duration = tDelayControl) has ended.\
\
In all other situations, the cascade controller is disabled.
#### Control
The current actual temperature *rActTemp* is permanently compared with the current setpoint temperature when the cascade controller is enabled (PI controller, *xEn* = TRUE, expiration of the duration **tDelayControl**, no limit value violation at the input *rActTemp*) and depending on the amount / sign of the difference or on the controller settings ( *rSetPtTemp* compared and depending on the magnitude / sign of the difference or depending on the controller settings (**rPI\_Kp** or **rPI\_Tn**) a displacement temperature is generated in the cascade controller.\
\
In heating mode (*rActTemp* < *rSetPtTemp*) a positive displacement temperature is thus generated in the range 0.0 - **rMaxRelativeSUP** K.\
In cooling mode ( *rActTemp* > *rSetPtTemp* ) thus a negative offset temperature is created in the range 0.0 - **rMinRelativeSUP** K.\
In the fully regulated state ( *rActTemp* = *rSetPtTemp* ) the displacement temperature does not change.\
\
This displacement temperature is then added to the current setpoint temperature and, if necessary, limited to the calculated limits *rMinSUPTemp* or *rMaxSUPTemp* .\
\
At output *rMinSUPTemp* the calculated minimum supply air setpoint temperature (*rActTemp* + **rMinRelativeSUP**, absolutely limited to **rMinSUP** or **rMaxSUP**) is permanently displayed.\
At output *rMaxSUPTemp* the calculated maximum supply air setpoint temperature (*rActTemp* + **rMaxRelativeSUP**, absolutely limited to **rMinSUP** or **rMaxSUP**) is permanently displayed.\
\
The current actual temperature *rActTemp* is monitored for compliance with limit values.\
At every limit violation (*rActTemp* < +5.0 °C or *rActTemp* > +50.0 °C) the cascade controller is deactivated.
#### Selection of the supply air setpoint temperature
The selection of the supply air setpoint temperature is carried out according to the following function table.
| *xFastHeatEn* | *xFNCEn* | *rActTemp* within limit values | *xEn* | Supply air setpoint temperature | Notes |
| ------------- | -------- | ------------------------------ | ----- | --------------------------------------- | ------------------------------------------- |
| TRUE | X | X | X | **rMaxSUP** | Special operating mode ‘Rapid heating’ |
| FALSE | TRUE | X | X | **rMinSUP** | Special operating mode ‘Free night cooling’ |
| FALSE | FALSE | FALSE | X | *rSetPtTemp* | Actual temperature limit violation |
| FALSE | FALSE | X | FALSE | *rSetPtTemp* | Control lockout |
| FALSE | FALSE | TRUE | TRUE | *rSetPtTemp* + displacement temperature | Normal operation |
Legend: X = any
#### Formation of the current supply air setpoint temperature *rSetPtSUPTemp*
The current supply air setpoint temperature *rSetPtSUPTemp* is formed from the supply air setpoint temperature, extended by a manual override module.
| Supply air setpoint temperature | **eManModeN** | *rSetPtSUPTemp* | Notes |
| ------------------------------- | ------------- | ------------------------------- | ---------------------------------------- |
| X | eMANNUM.Auto | Supply air setpoint temperature | Manual override module in automatic mode |
| X | eMANNUM.Man | **rManValue** | Manual override module in manual mode |
Legend: X = any
#### Cascade controller for active cooling mode (PI controller)
This cascade controller is used to generate the supply air setpoint temperature for a cooling unit from
1. Current setpoint temperature (maximum value of (*rSetPtTemp* + 1) and *rSetPtTempCool*)
\
2\) Current actual temperature (exhaust air or room temperature) in °C\
\
taking into account the following limits:\
\
Minimum value - output signal of the cascade controller: rMinSUPTemP - (maximum value of (rSetPtTemp + 1) and rSetPtTempCool)\
\
Maximum value - output signal of the cascade controller: rMaxSUPTemP - (maximum value of (rSetPtTemp + 1) and rSetPtTempCool)\
\
The supply air setpoint temperature is generated after the enabling / disabling of the main cascade controller, provided that input xEnCool is active (= TRUE).\
\
The cascade controller for active cooling mode is enabled if the following conditions described below are all met at the same time:\
\
1\) The special operating mode rapid heat-up is blocked (xFastHeatEn = FALSE).\
\
2\) The special operating mode free night cooling is blocked (xFNCEn = FALSE).\
\
3\) The current actual temperature rActTemp does not violate its absolute limits (+5.0 - +50.0 °C).\
\
4\) The control is enabled (xEn = TRUE) and the switch-on delay (duration = tDelayControl) has ended.\
\
5\) The input xEnCool is enabled (xEnCool = TRUE).\
\
In all other situations, the cascade controller for active cooling mode is blocked.
#### Control
The current actual temperature *rActTemp* is, when enabled, continuously compared with the current setpoint temperature (maximum value of (*rSetPtTemp* + 1) and *rSetPtTempCool*) and, depending on the magnitude/sign of the difference or depending on the controller settings (**rPI\_Kp** or **rPI\_Tn**) an offset temperature for active cooling mode is generated in the cascade controller.\
\
In the heating case (*rActTemp* < current setpoint temperature) a positive offset temperature is created in the range 0.0 - minimum value - output signal of the cascade controller for active cooling mode K.\
In the cooling case (*rActTemp* > current setpoint temperature) a negative offset temperature is created in the range 0.0 - maximum value - output signal of the cascade controller for active cooling mode K.\
In the fully regulated state (*rActTemp* = current setpoint temperature) the offset temperature does not change.\
\
This offset temperature is then added to the current setpoint temperature and, if necessary, limited to the calculated limits *rMinSUPTemp* or *rMaxSUPTemp* limited.\
\
The current actual temperature *rActTemp* is monitored for compliance with limit values.\
At every limit violation (*rActTemp* < +5.0 °C or *rActTemp* > +50.0 °C) the cascade controller is deactivated.
#### Selection of the supply air setpoint temperature
The selection of the supply air setpoint temperature is carried out according to the following function table.
| Enable cascade controller for active cooling mode | *rActTemp* within limit values | Supply air setpoint temperature | Notes |
| ------------------------------------------------- | ------------------------------ | -------------------------------------------------------- | ------------------ |
| FALSE | X | Maximum value of (*rSetPtTemp* + 1) and *rSetPtTempCool* | Controller blocked |
| X | FALSE | Maximum value of (*rSetPtTemp* + 1) and *rSetPtTempCool* | limit violation |
| TRUE | TRUE | Current setpoint temperature + offset temperature | Normal operation |
Legend: X = any
#### Formation of the current supply air setpoint temperature *rSetPtSUPTempCool*
The current supply air setpoint temperature *rSetPtSUPTempCool* is formed from the supply air setpoint temperature, extended by a manual override module.
| Supply air setpoint temperature | **eManModeNCool** | *rSetPtSUPTempCool* | Notes |
| ------------------------------- | ----------------- | ------------------------------- | ---------------------------------------- |
| X | eMANNUM.Auto | Supply air setpoint temperature | Manual override module in automatic mode |
| X | eMANNUM.Man | **rManValueCool** | Manual override module in manual mode |
Legend: X = any
### Codesys
InOut:
| Scope | Name | Type | Initial |
| ----------- | ---------------------- | ------- | ------------ |
| Input | `xEn` | `BOOL` | |
| Input | `rActX` | `REAL` | 9 |
| Input | `rSetPtminHum` | `REAL` | 40 |
| Input | `rSetPtmaxHum` | `REAL` | 70 |
| Input | `rSetPtTemp` | `REAL` | 21 |
| Input | `rSUPTemp` | `REAL` | 20 |
| Output | `rSetPtSUPxHumidify` | `REAL` | |
| Output | `rSetPtSUPxDehumidify` | `REAL` | |
| Output | `rMinSUPX` | `REAL` | |
| Output | `rMaxSUPX` | `REAL` | |
| Output | `rSetPtxHumidify` | `REAL` | |
| Output | `rSetPtxDehumimdify` | `REAL` | |
| Output | `xEnHum` | `BOOL` | |
| Output | `xEnDehum` | `BOOL` | |
| Input Const | `rPI_Tn` | `REAL` | 400 |
| Input Const | `rPI_Kp` | `REAL` | 1.4 |
| Input Const | `rMaxHumSUP` | `REAL` | 80 |
| Input Const | `rMinHumSUP` | `REAL` | 30 |
| Input Const | `tDelayControl` | `TIME` | TIME#5m0s0ms |
| Input Const | `rP` | `REAL` | 980.0 |
| Input Const | `rManValueDehum` | `REAL` | |
| Input Const | `eManModeNDehum` | eManNum | eManNum.Auto |
| Input Const | `rManValueHum` | `REAL` | |
| Input Const | `eManModeNHum` | eManNum | eManNum.Auto |
---
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