History trend widget

The data collected and stored from the data logger can be analyzed using the History Trend widget.

This is a two-step process:

• first you create a trend buffer to collect data for specified tags at specific points in time,
• then you configure a History Trend widget to display the collected data in a graphical format.

See "Data logging" for details on how to create a trend buffer

To display a history trend:

1. Drag and drop the History Trend widget from the widget gallery to the page.

2. Attach the trend buffer that you want to draw to the Curve n Value. Data is always plotted against time.

History trend widget properties

Property	Description
Num Curves	Number of trend curves to be displayed
Page Duration	Time window to show
End Time	End time of the time window This parameter can be used to scroll the time window. When zero, the end time is the current system time.
Starting Position	Specifies where the curve begin to be drawn when the page is opened (can be left, center or right).
Behavior	Definition of: Min/Max of Y axis Number of tickets to draw on the axes Background image
Text	Trend title and font properties (font size, label, etc.)
Grid	Properties of grid presentation (colors)
Cursor	Properties of cursor presentation (enable and color)
X Scale	Properties of X Scale presentation
Y Scale	Properties of Y Scale presentation
Curve "n"	Buffer that contains the tag's values to plotted in the trend widget. Select Trend select the trend buffer to display Attach To select a tag (string) that will contain the name of the trend buffer to display (it is an indexed trend buffer selection)

Tag values can be scaled using the X Forms in the Attach to dialog. See ""Attach to" parameters" for details.

Printing historical trend widget

The historical trend widget can be found and used from the print report gallery.

Using the “attach to tag” feature is possible to use tags to define some properties of the historical trend to print at runtime:

• Page Duration
• End Time
• Curve Name

"Page Duration" with "End Time" define the piece of the trend buffer to print. "Curve Name" can be used to select the curve to show. An empty string means no curve to show.

SetTrendView() and ScrollTrendToTime() are display macros and have no effect on report printing.