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# ControlP
## `ControlP` (FB)
FUNCTION\_BLOCK ControlP
### Short description
> Proportional-acting controller (P-controller)\
> The direction of action (inverted / direct) is also adjustable.\
> Typical application: control loops with actuators that have an integrating/storage character.
### Representation
### Interfaces
#### Inputs
| Name | Data type | Value range | Initial value | Function |
| ----- | --------- | ----------- | ------------- | ------------------------ |
| *rX* | REAL | | | Analog measured value |
| *rW* | REAL | | | Analog setpoint |
| *xEn* | BOOL | | | Enable of the controller |
#### Outputs
| Name | Data type | Value range | Initial value | Function |
| -------------- | --------- | ----------- | ------------- | ------------------------ |
| *rY* | REAL | | 0.0 | Controller output signal |
| *rDiff* | REAL | | | Control deviation |
| *xLimitActive* | BOOL | | | Status - limit exceeded |
#### Setpoints / parameters
| Name | Data type | Value range | Initial value | Function |
| -------------- | ------------ | ----------- | --------------------- | -------------------------------------------------------- |
| **rMax** | REAL | | 100.0 | Upper absolute limit of the output signal |
| **rMin** | REAL | | -100.0 | Lower absolute limit of the output signal |
| **rKp** | REAL | 0.0 … | 2.0 | Gain factor |
| **rOffset** | REAL | | 0.0 | Offset |
| **rYDisabled** | REAL | | 0.0 | Disabled value |
| **eAction** | eControlMode | | eControlMode.Inverted | Direction of action of the controller (Inverted, Direct) |
| **eManModeN** | eManNum | | eManNum.Auto | Operating mode for the controller output signal |
| **rManValue** | REAL | | | Output signal in manual mode |
### Function description
#### General
This function block contains a proportional-acting controller (P-controller).\
The controller's output signal *rY* is calculated when the controller is enabled (*xEn* = TRUE) and in the controller's automatic operating mode (**eManModeN** = eManNum.Auto) is calculated as follows:\
\
\
\&#xNAN;*rY* = **rKp** \* ((measured value + offset) - (setpoint))\
\
\
Depending on the controller's direction of action **eAction** the measured and set values are determined as follows:
| **eAction** | measured value | setpoint | Formula | Function |
| --------------------- | -------------- | -------- | ------------------------------------------------- | ------------------------------ |
| eControlMode.Inverted | *rW* | *rX* | *rY* = **rKp** \* ((*rW* + **rOffset**) - (*rX*)) | Direction of action - Inverted |
| eControlMode.Direct | *rX* | *rW* | *rY* = **rKp** \* ((*rX* + **rOffset**) - (*rW*)) | Direction of action - Direct |
#### Enable input *xEn*
If the enable input is not active (*xEn* = FALSE) the disabled value **rYDisabled** is transferred to the output *rY* (precondition: **eManModeN** = eManNum.Auto) and limited by the absolute limits.\
\
With the enable input active (*xEn* = TRUE) the output signal is calculated according to the formula above and passed to the output *rY* (precondition: **eManModeN** = eManNum.Auto) and limited by the absolute limits.
#### Control deviation *rDiff*
The control deviation is calculated according to the following formula and passed to the output *rDiff* .\
\
\&#xNAN;*rDiff* = measured value - setpoint
#### Absolute limits **rMin** and **rMax**
The controller's output signal *rY* is limited downwards by the absolute limit **rMin** and upwards by **rMax** .\
The absolute limit **rMin** is set to the current value of **rMax** - 0.1 if it is >= the current value of **rMax** .\
The only exception is manual operation for the controller output signal (**eManModeN** = eManNum.Man).
#### Status - limit exceeded *xLimitActive*
The limit-exceeded status is activated (*xLimitActive* = TRUE) if a limit exceedance exists.\
The status of the limit exceedance is not set (*xLimitActive* = FALSE) if no limit exceedance exists.\
\
A limit exceedance exists if the controller's output signal *rY* reaches / exceeds the upper limit **rMax** or reaches / falls below the lower limit **rMin** .
#### Operating mode for the controller output signal **eManModeN**
The parameter **eManModeN** allows switching the output signal *rY* from automatic to manual mode and vice versa.\
In manual mode the output signal *rY* takes over the output signal in manual mode **rManValue**.\
The setpoint / parameter **rManValue** is overwritten with the current value of the output signal at every transition into automatic mode *rY* .
| **eManModeN** | *rY* | Function |
| ------------- | -------------------------------------------- | ------------------------------ |
| eManNum.Auto | signal according to formula / disabled value | Automatic mode - output signal |
| eManNum.Man | **rManValue** | Manual mode - output signal |
### CODESYS
InOut:
| Scope | Name | Type | Initial |
| ----------- | ------------- | ------------ | --------------------- |
| Input | `rX` | `REAL` | |
| Input | `rW` | `REAL` | |
| Input | `xEn` | `BOOL` | |
| Input Const | `rYMax` | `REAL` | 100 |
| Input Const | `rYMin` | `REAL` | -100 |
| Input Const | `rKp` | `REAL` | 2 |
| Input Const | `rOffset` | `REAL` | 0 |
| Input Const | `rYDisabled` | `REAL` | 0 |
| Input Const | `eAction` | eControlMode | eControlMode.Inverted |
| Input Const | `eManModeN` | eManNum | eManNum.Auto |
| Input Const | `rManValue` | `REAL` | |
| Output | `rY` | `REAL` | 0 |
| Output | `rDiff` | `REAL` | |
| Output | `xLimitAktiv` | `BOOL` | |
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