Stream Gateway provides a built-in rich data logging capability.


Any Tag can be logged using one or two different methods. These methods are called "Historical Models". Refer to Tags / Historical configuration for more details about assigning tags to historical models.


From Stream Explorer, select Historical and click on the Add button.


Main Tab:



Basic

  • Active: Enables or disables any logging associated with this historical model.
  • Name: Unique name for the historical mode.
  • Database: Select either (SQLite) or (MS SQL Server).


SQLite Settings:

  • Path: (Optional). When left blank, the SQLIte database file will be stored in the application folder under the "Historical" folder. If you want to save the database in a separate location, set the folder path in this field.    


MS SQL Server Settings:


  • Host: SQL Server instance name.
  • Database name: Choose any meaningful name.
  • Username and Password: User credentials to access the SQL server.  
  • Use this connection string: When selected, the entered connection string will be used instead of the above setings.




Storage Settings Tab:



  • Type: Select one of the two options:


a. OnValueChange:


    • Minimum Value Change: Save the data only when the Tag's value changes by a specific absolute value.
    • Log On Timestamp Change: Save the data when Tag's timestamp changes (i.e. updated from its data source).


b. Periodic: Stores the data cyclically each specified number of seconds (Sample Interval).

    • Sample Interval: Save the data cyclically each specified number of seconds.


  • Save Interval: At first, Tags values are stored in the application internal memory in a queue. Later, it's written to a disk after the (Save Interval) is elapsed.
  • Keep Period: Set here the number of days you want to keep the historical data for this historical model.




Control Tags Tab:



  • Enable Tag: Storing is only active if this tag is True.
  • Take Sample When this Tag is True: Stream will take a snap shot for readings when this Tag is True. This works side-by-side with the storage settings.



  • Read-only: When checked, this historical model is only used for data reading not writing.
  • Enable writing while server is in Standby mode: In redundant setup, enable the standby server to write to the database.
  • Enable fetching extra points if needed (while reading): if the data returned doesn't cover the whole time period, fetch and substitute extra points.


Note: Any defined historical model will appear as an option in historical configuration of tags as shown in the below screen shot.


             



Note: Tags that have status of "Not Initialized" are not stored until their status change to something else (e.g. Normal or any alarm state)


Note: In case of using SQLite, It's possible (and recommended) that you define more than SQLite database and assign different tags and/or different storage settings to it.