Tag-filter expressions
The tag filter expression in the cross-correlation analysis is an optional parameter. When nothing is specified, the analysis will be performed for all indexed tags. TrendMiner, however, is often connected to a variety of data sources, containing data of different process units or even completely different plants. To avoid seeing a lot of spurious correlations, or to focus your analysis on a specific set of tags, a tag filter expression can be used.
The tag filter expression works similarly to the tag and asset browser. A couple of filter expressions and how they impact the list of analyzed candidates is shown below:
Note
The filter expression is not case-sensitive.
Note
If Unit1*TI* is coming from historian with prefix this expression will not lead to results. *Unit1*TI* would be needed.
"Temp" or "*Temp*": tag name needs to contain "temp".
Unit1*TI*: tag name needs to start with Unit1 and contain TI in the remainder of the name.
Unit1*TI*.PV: tag name needs to start with Unit1, contain TI in the name and end on ".PV".
Using a tag filter expression allows you to focus your analysis, and also decreases computation time.