Trend

Use a trend symbol to view values of one or more data items plotted against time on a graph. Trends are typically used to display time-series data, though they may also include non-time-series data.

To add a trend to a display, select the trend symbol icon from the Symbol Gallery and then drag your data item from the search results onto the display.

1. Traces are the lines drawn on a trend that represent a series of data points from a data item. When a trace is continuous, a line is drawn from measurement to measurement. When a trace is discrete, the value is propagated forward until a new value is recorded in the database. This results in horizontal and vertical lines for the tag (stepped trace).

2. Trend legend provides quick details about data items that are part of a trend and include the data item's name, value, and unit of measure. The color of the legend corresponds with the trace line used to draw the data on the trend. Clicking an item on the trend legend will highlight the trace on the legend.

3. Value scale shows the range of values that appears within a trend.

4. Trend cursor helps you view your data with precision by showing a trend line, a legend value, and a timestamp. Trend cursors are synchronized across multiple trends. Moving the trend cursor over a trace changes the legend value. The legend value is the value of the data on a trace at the time selected by the trend cursor. You can only view trend cursors when you exit Design mode. (See Monitor trends with trend cursors.)

Value scale

Data values on a trend appear within a range of values that is referred to as the value scale. By default, the value scale shows a separate scale for each data item (represented by a trace). The scale indicates the highest high and lowest low values of the data items during the time range of the display.

You can change the value scale to use a single consolidated scale for all data items, as opposed to separate scales for each data item. Value scale settings persist for each trend even after you close a display. You can also configure the maximum and minimum values of the value scale by choosing between the maximum and minimum of the trend's plotted values or its pre-configured maximum and minimum values. (See Configure trend options and style.)

Default configuration

Administrators can set the default configuration for new trend symbols across all displays based on an existing trend symbol. You can set the defaults for as many traces as shown in the current trend. For example, if the trend used to set defaults has two traces and you add a trend with three traces, the third trace will use system defaults. For more information about display defaults, see the Default display and symbol configuration topic in the AVEVA PI Vision Installation and Administration Guide. The symbol configuration settings which a default can be set for are:

• Trend Options

  • Foreground Color

  • Background Color

  • Grid

• Value Scales

  • Scale Type

  • Invert Scale

  • Scale Label

• Time Range

  • Time scale

• Trace Options

  • Color

  • Legend Label

    • Custom cannot be saved as a default

    • Only settable as a default if all traces have the same label type

• Font

  • Name

  • Size