Filter
Top Products
Chapter 6 Historical Data Logging and Extraction
© National Instruments Corporation 6-5 BridgeVIEW User Manual
If the Citadel Path is empty, the File Dialog function is executed. This
brings up a File dialog box that lets the operator select the directory
containing the historical data files.
The example then uses the
tag list
returned by the Get Historical Tag
List VI to set up a list of names in the front panel Tag List listbox, found by
selecting List & Ring»Single Selection Listbox from the controls palette.
It uses the
first timestamp
output to initialize the
Start Timestamp
control on the front panel. By default, the example displays the first
60 seconds worth of data on the historical data display. Historical data is
displayed using the XY Graph indicator named Historical Trend Display.
The Read Historical Trends VI returns historical data from Start
Timestamp
to
Stop Timestamp
for the tags that are selected in the Tag
List listbox and returns data in a form that can be wired directly to an
XY Graph.
The shift register in the while loop is used to detect user input changes on
the operator interface by remembering the previous Start Timestamp
,
Stop Timestamp
, and the selected
tag list
. If any of these controls are
changed, historical data is retrieved for the new settings and the XY Graph
indicator is updated.