# DampingT1

## `DampingT1` (FB)

FUNCTION\_BLOCK DampingT1

### Short description

> Temporal filtering of an analog input signal\
> \
> Typical application: filtering of a sensor raw value

### Representation

<figure><img src="/files/6124e5409335807fd560b42242237e398cf781cb" alt=""><figcaption></figcaption></figure>

### Interfaces

#### Inputs

| Name  | Data type | Value range | Initial value | Function           |
| ----- | --------- | ----------- | ------------- | ------------------ |
| *rIn* | REAL      |             |               | Analog value input |

#### Outputs

| Name   | Data type | Value range | Initial value | Function                     |
| ------ | --------- | ----------- | ------------- | ---------------------------- |
| *rOut* | REAL      |             |               | Filtered analog value output |

#### Setpoints / parameters

| Name              | Data type | Value range | Initial value    | Function                       |
| ----------------- | --------- | ----------- | ---------------- | ------------------------------ |
| **tTimeConstant** | TIME      | 5s…         | T#10s            | Filter - time constant         |
| **rInitValue**    | REAL      |             | 100              | Initial value                  |
| **eInitial**      | eInit     |             | eInit.InputValue | Selection of the initial value |
| **tInitDelay**    | TIME      |             | T#5s             | Start delay - initialization   |

### Function description

#### General

The analog input signal *rIn* is examined at intervals of the sampling time (here: 1s, fixed) for changes in its value.\
If the current value at the input *rIn* at time t differs from the value at the output *rOut* at time t-sampling time, then the current output value *rOut* at time t is calculated according to the following algorithm:\
\
\
\&#xNAN;*rOut* = *rOut* (t-sampling time) + ((*rIn* - *rOut* (t-sampling time)) \* (sampling time / **tTimeConstant**))\
\
\
Legend:&#x20;

1. *rOut* = filtered analog value output at time t
2. *rOut* (t-sampling time) = filtered analog value output at time t-sampling time
3. *rIn* = analog value input at time t
4. Sampling time = 1s
5. **tTimeConstant** = filter - time constant
6. t = current time

{% hint style="info" %}
**Rules for setting the filter time constant tTimeConstant**

**tTimeConstant** > (sampling time \* 5)\
**tTimeConstant** = 0: *rOut = rIn*
{% endhint %}

#### Type of initialization **eInitial**

This setpoint / parameter determines the type of initialization of the analog value input *rIn* is defined.\
The initialization is performed once after each CPU restart.\
\
The following options are possible:

| Type                    | Initialization value | Note                       |
| ----------------------- | -------------------- | -------------------------- |
| eInit.InitValue         | **rInitValue**       | Configurable initial value |
| eInit.InputValue        | *rIn*                | Input value                |
| eInit.InputValueDelayed | *rIn*                | Delayed input value        |

The initialization is performed continuously regardless if the setpoint / parameter **tTimeConstant** has the value T#0s.

### CODESYS

InOut:

| Scope       | Name            | Type   | Initial          |
| ----------- | --------------- | ------ | ---------------- |
| Input       | `rIn`           | `REAL` |                  |
| Input Const | `tTimeConstant` | `TIME` | TIME#10s0ms      |
| Input Const | `rInitValue`    | `REAL` | 100              |
| Input Const | `eInitial`      | eInit  | eInit.InputValue |
| Input Const | `tInitDelay`    | `TIME` | TIME#5s0ms       |
| Output      | `rOut`          | `REAL` |                  |


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