Overview
HistorianTables organize HistorianTags for logical grouping and management. A table defines the storage parameters for a specific set of tags. This includes how and when tags are saved, storage locations, and triggers for data storage (such as time intervals or value changes). HistorianTables allow customization of data retention periods. They are used to structure historical process data for retrieval and analysis, supporting applications such as process optimization, troubleshooting, and reporting.
Configuring HistorianTables
You can create as many HistorianTables as you need to organize your archives better and optimize for disk space and performance. To create a new HistorianTable, follow the steps below:
- Access Historian / HistorianTables.
- Click on the Plus icon.
- Fill in the fields and set the HistorianTable settings. The following section on this page describes each option available.
- Click OK.
Configuration option availability
Specific options may be unavailable depending on the selected database or property chosen. For example, you can't define a trigger if you check the Normalized option for the new Historian Table. Therefore, it's essential to consider your options carefully.
The new table will show up on the Datagrid list. You can edit the HistorianTable by selecting and changing the desired property if you need to. Alternatively, you can choose the HistorianTable and click the Pencil icon.
It's a good practice to store only the necessary data at the required frequency. You can use features like Deadbands, On Tag Change, or Trigger events to achieve this. These features help you organize your storage and only save important data without overloading the system or slowing down data recovery.
HistorianTable Properties
When configuring a HistorianTable, you need to specify some properties defining when and how data will be archived. The following table describes each of the properties available.
Field | Description | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
ArchiveLocation | Defines the Archive Location used. By default, the TagHistorian based on SQLite is used. For more information, access the Historian Storage Locations. | ||||||||||||
TableName | Name of the HistorianTable object. For other databases, this name is used as a logical grouping name. | ||||||||||||
AutoCreate | If you select this option, the Historian module will verify if this table has already been created in your SQL database. If the table does not exist, it will create a new one. | ||||||||||||
SaveOnChange | If you check this option, an action event to archive Tag data is generated whenever the Tags value changes. | ||||||||||||
Trigger | The Trigger option enables you to choose an event that, when it happens, will trigger the archiving of all Tags associated with the current HistorianTable in the database. You can use any tag, object, or property from the object's namespaces as a trigger. Click the Elllipses button (...) to access all options available. | ||||||||||||
TimeDeadband | Specify the minimum logging interval using HH:MM:SS:MS (Hours, minutes, seconds, milliseconds) format. This parameter determines the duration the system must wait after storing one tag value before storing a new one. It prevents excessive record creation in the database, especially if you're using the SaveOnChange option. If set as zero, this setting is inactive. As an example, consider you set a five-second deadband. After a Tag is archived, the counter begins. If the counter doesn't reach five seconds, no Tag information will be saved, independent of how big its value changes. The table below exemplifies the example.
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LifeTime | Set the duration in days for retaining records on the Storage Location. The system automatically deletes data older than the specified lifetime. If you set the value to 0 or leave it blank, the system will not perform automatic data deletion, ensuring the data remains untouched. | ||||||||||||
SaveQuality | When checked, a column in your SQL DB stores the Quality property of the Tag argon with the value. The quality level defines how reliable the Tag is, and it follows the OPC standard specification. By checking this option, only points with real data will be displayed when you access a graph. Check more about this option in the section on this page. | ||||||||||||
Normalized | When checked, the system uses the Normalize table schema for SQL databases or the Standard schema otherwise. For more information on SQL database schemes, refer to the Archiving Process. | ||||||||||||
ValueColumnsType | Select the type of value to be stored in the value columns, which defines the Tags' value type in the SQL database. You can change this property only when creating the HistorianTable. | ||||||||||||
Description | Description for this HistorianTable object. |
Save Quality
In certain instances, the graph may exhibit lines and values even in timestamps where there is no data present. For instance, when you access a graph that you know lacks data and you see a continuous line connecting the endpoints of existing data points, despite the absence of data in between, you can infer that you are leading with unreal information. If you click on such areas, the value shown can lead you to misleading cursor values, as no data exists for those specific moments.
To address this issue, you can remove the line connecting the points of the graph where there is no data. This can be achieved by enabling the SaveQuality property in your HistorianTable, as depicted in the image below. If the SaveQuality option is not available in any column, you can enable it by right-clicking on the top of any column name and select SaveQuality.
You can also configure this option when creating the HistorianTable by checking the SaveQuality option, as shown in the image below.
The image below demonstrates a graph without lines in areas where no data exists, offering a clearer representation.
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