- 14 Dec 2021
- 2 Minutes to read
- Updated on 14 Dec 2021
- 2 Minutes to read
Introduction to Historian
N3uron Historian is a high-performance time-series storage system based on a non-SQL database (MongoDB). In x64 bit systems, the ModgoDB instance is automatically installed in the N3uron installation folder, so Historian is ready to store data as soon as installation is complete. In x32 and ARM architectures, the user must first install MongoDB so that Historian can then be configured to store the data in this ModgoDB instance.
N3uron Historian can store any tag values that have been collected locally in the same node or those collected remotely by other nodes and received in the Historian node through N3uron Links.
Historian provides efficient data compression and partitioning mechanisms, allowing the storage of massive volumes of time-series data without reducing its performance over time.
Historian stores events (changes in value, quality, or timestamp). Data can be retrieved from the storage in different modes:
- Raw: Data retrieved contains all the values for all events stored in the database.
- Aggregated: Data is consolidated into aggregation periods. The following aggregation methods are available:
- avg: Time-weighted average
- min: Minimum value during the aggregation period
- max: Maximum value during the aggregation period
- first: First value during the aggregation period
- last: Last value received during the aggregation period
- Delta: Data retrieved contains all the values of all events displaying incremental changes compared to any previous event that is larger than the configured deadband. It only contains the second event (the one taking place after the first event that surpassed the deadband).
- Filter: Data retrieved contains all the values for all events displaying changes compared to any previous event that is larger than the configured deadband. In this case it contains both events, the one before the change that surpassed the deadband and the one after the change.
Figure 7. Delta and Filter chart
Data stored in Historian can be retrieved using the following methods:
- WebUI: Includes a rich HTML5 interface to retrieve and visualize data in charts and data tables (raw and aggregated data). Data can be also exported to CSV files. The historical data retrieved can be located in the same N3uron node as the WebUI or in a different N3uron node, providing that the nodes are connected through a N3uron Link.
- REST API Server: By using the optional RestApiServer module, historical data can be retrieved in JSON format using REST API calls (raw data and aggregated data). The historical data retrieved can be located in the same N3uron node as the REST API server or in a different N3uron node, providing the nodes are connected through a N3uron Link.
- MongoDB client: Direct connection to the MongoDB database to retrieve data in raw mode.
Figure 8. Historian charts from the WebUI
Steps to configure Historian:
- Step 1: Create the Historian module instance in the N3uron node where data will be stored.
- Step 2: Configure the historization for each tag pointing to the Historian module. If the Historian module is located in a different N3uron node, then the module name will be “NodeName/ModuleName”.
For more details about N3uron Historian configuration, please refer to the Historian configuration example chapter.