You can Base a TrendSpec Definition on the Definition of Another Ad Hoc Trend or write a TrendSpec definition from the beginning. Use a suitable text editing application to write the definition, or enter the definition directly into the relevant Mimic’s Script Editor.
Each Trend definition has to include the following identifiers and values, with commas separating, and parentheses surrounding, each subsection:
TREND
(
TRACE(<Data Mode>,<Y-Axis Name>,
SOURCE (<Source Name>)),
XAXIS(<X-Axis Mode>),
YAXIS(<Y-Axis Name>)
)
TREND, TRACE, SOURCE, XAXIS, and YAXIS are the definition’s Section Identifiers. Of these, the SOURCE section has to be specified within the TRACE section, and the TRACE, XAXIS and YAXIS sections have to be specified within the overall TREND section.
The entries in angle brackets <> indicate the Mandatory Values that have to be included in each Trend definition. Within each subsection, you can optionally specify further values in addition to these mandatory values—such additional Optional Values have to be specified after the Mandatory Value(s) in each subsection. The <Y-axis Name> mandatory values in the TRACE and YAXIS subsections have to be identical to each other.
Do not include the angle brackets <> in a Trend definition—they are used within the documentation to indicate where the actual content differs, depending on the required Trend structure.
The section and optional identifiers used in a TrendSpec definition are case insensitive. Any strings or expressions that reference an item in the ClearSCADA database are case sensitive.
Example:
TREND (TRACE(RawHistoric, 'Temperature',SOURCE ('Point3.Historic')),
XAXIS(RelativeLatest),YAXIS('Temperature'))
(For an ad hoc Trend that displays a trace of raw historic data for the point named Point3. The data indicates the point’s temperature (with the Y-axis being labelled ‘Temperature’). The X-axis constantly updates, so that the data shown is for a time that is relative to the latest value plotted on the Trend.)
For a TrendSpec definition to be used in script or a URL, the definition has to be appended to the rest of the script or URL content. This content needs to include the full path to the ad hoc Trend (typically SCX:////Trend/). For more information, see Base a TrendSpec Definition on the Definition of Another Ad Hoc Trend and Example Configuration.
With any Trend definition, ClearSCADA uses the ViewX defaults for any settings—such as the X-Axis offset and interval, or the Y-Axis scale—that are not specified in the definition. These defaults are specified on the Trends tab of the ViewX Options window (see Define the Default Settings for New Trends).