Thinning Rules
Thinning rules are used to specify what method of deletion will be used to thin data in the VHS and also configure to which specific groups of data the selected method should be applied.
The VHS Data Analyzer utility only allows for the creating and configuration of thinning rules. Another utility, VHS Data Thinner is used to execute the deletion of entries in the VHS.
Thinning rules are composed of two main components: thinning models and thinning rules.
- Thinning models determine the method for thinning data in the VHS.
- Thinning rules specify to which points a model will be applied.
The Configure Thinning Rules dialog box is used to view, create and edit thinning rules; it can be opened by selecting either Configure Thinning Rules… from the File menu, or by choosing a single point and selecting Create Thinning Rule… from the right-click context menu. Both options open the Configure Thinning Rules dialog box, only Create Thinning Rule… will automatically input the selected point’s LongID into the Udc/FacilityTag field.
Thinning models can be viewed, created, and edited by clicking View/Edit Models from within the Configure Thinning Rules dialog box.
Thinning rules are saved to the XML file specified in the path at the top of the dialog box. This is the file that will be used by the VHS Data Thinner to delete data from the historian. Multiple configurations of thinning rules may be created by saving different sets to different files. When the dialog box first opens, the last XML file is opened and loaded. To load a new XML file, browse to select the file and click Load File. To save the current rules to a different XML file, select the new file using …, then click Save to File in the bottom corner of the dialog box. Changes made on the screen will only be saved to the XML file using the Save to File button. If the dialog box is closed without saving to the XML file, all changes will be lost. Clicking Cancel will throw out all the changes, although you will be warned that you are about to lose all your changes.
Note: At least one Thinning Model must be defined before thinning rules can be created.
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