Technical Reference Manual - InduSoft

Alarms, Events, and Trends
Trend worksheet
The Trend folder enables you to configure history groups that store trend curves. You can use the Trend
worksheet to declare which tags must have their values stored on disk, and to create history files for trend
graphs. The project stores the samples in a binary history file (*.hst), and shows both history and on-line
samples in a screen trend graph.
The Trend worksheet is executed by the Background Task module (see Execution Tasks). It handles the
saving of trend data to the history, but it does not display that data to the operator; the Trend Control screen
object, available on the Graphics tab of the ribbon, must be created and configured in a screen in order to
display trend data.
To create a new Trend worksheet, do one of the following:
• On the Insert tab of the ribbon, in the Task Worksheets group, click Trend;
• Right-click the Trends folder in the Project Explorer, and then click Insert on the shortcut menu; or
• Click New on the Application menu, click the File tab, and then select Trend Worksheet.
To edit an existing Trend worksheet, double-click it in the Project Explorer.
The Trend worksheet is divided into two areas:
Trend worksheet
• Header area (top section), which contains information for the whole group
• Body area (bottom section), where you define each tag in the group. This section contains several columns
(only two are shown in the preceding figure).
Use the Header parameters on this worksheet as follows:
• Description field: Type a description of the worksheet for documentation purposes.
• Type combo box: Click the arrow button to select a trend history format from the list. The available options
are:
• Proprietary
• File Format: Binary
• Default Path: …\project_name\Hst\GGYYDDMM.HST, where:
• Database
• YY = Two last digits of the year
• MM = Month
• DD = Day
Note: IWS provides the HST2TXT.EXE and TXT2HST.EXE programs, which enable you to
convert trend history files from binary ( .hst ) to text ( .txt ) and vice versa. For more
information about these programs, see Converting Trend History Files from Binary to Text and
Converting Trend History Files from Text to Binary.
• Database Type: Chosen by the user
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