30. Downsample Datum Filter¶
The Downsample Datum Filter provides a way to down-sample higher-frequency datum samples into lower-frequency (averaged) datum samples. The filter will collect a configurable number of samples and then generate a down-sampled sample where an average of each collected instantaneous property is included. In addition minimum and maximum values of each averaged property are added.
This filter is provided by the Standard Datum Filters plugin.
30.1 Downsample property handling¶
The method of deriving a downsample property value depends on the property classification of each property.
| Class. | Description | Method |
|---|---|---|
i |
instantaneous | The average of the collected values is used. Optional minimum and maximum property values can also be generated. |
a |
accumulating | The most recent (last seen) of the collected values is used. |
s |
status | The most recent (last seen) of the collected values is used. |
30.2 Settings¶
In addition to the Common Settings, the following general settings are available:
| Setting | Description |
|---|---|
| Sample Count | The number of samples to average over. |
| Sample Duration | A duration in seconds to collect samples within before generating an averaged output. Overrides the Sample Count setting. See the note below on how the sample times become clock-aligned. |
| Decimal Scale | A maximum number of digits after the decimal point to round to. Set to0 to round to whole numbers. |
| Property Excludes | A list of property names to exclude. |
| Min Property Template | A string format to use for computed minimum property values. Use %s as the placeholder for the original property name, e.g. %s_min. |
| Max Property Template | A string format to use for computed maximum property values. Use %s as the placeholder for the original property name, e.g. %s_max. |
30.2.1 Sample Duration¶
When this setting is configured, the resolved timestamp of each downsampled datum will be
clock-aligned based on the period configured. For example if 300 is configured, then
the resolved timestamps would have times exactly at 00:00, 00:05, 00:10 and so on.