Adding a Query to Plot Multiple Pens

A query is a request for all tags that match a given criteria.  It is saved as a text representation of the filter created using the fields at the top of the Tag Selector dialog. 

For example, the following filter settings:

… will be saved as the following query:

 

The query will plot all the tags that match the selection filter.  Be careful that this is not an excessive number of tags. The Preview button can be used to find out how many tags match the query before you attempt to plot them.

Queries have the advantage of being flexible. If new tags are added to the system that will match the query’s filter, you do not need to update the selected tag list – the query will find them the next time the HDV is used.

The steps to create a query are as follows:

1.   Open the Tag Selector dialog from the Historical Data Viewer.

2.   Define the filtering criteria using the fields in the Filter Tags/Create Query section of the Tag Selector.

3.   [optional] Click the Remove All button.

While you may combine multiple queries or select queries and tags to get a list which is the sum of both, it is more common to run only one query at a time.

4.   Click the Add Query button to add the query to the list of Selected Tags / Queries for Plotting

5.   Click the Preview button to check that the tag list from the query is what you expect.

6.   Click the Plot button to return to the HDV and plot the tags.