Option 4.2.6. Configure a Reference Line

Creating a line as a reference for other lines can be useful in many instances.

A reference line is a horizontal line that will be updated.


Reference line configuration.

Reference line Axes.

Reference file configuration.

Reference file rows.

Reference Line overview

The reference line can be create from

An expression

A reference file that is created by the Trending module through the Runtime Actions tab in the CIMPLICITY Trend Control Properties dialog box.

The lines are updated as follows.

Value Source

How Trending Updates the Reference Line


Trending takes the latest value of the expression and draws a horizontal line with the value. If the value of the expression changes, Trending updates the reference line.

Reference file

Retrieves values (from a reference file) that are exported into the reference file at runtime.

Reference line configuration

Reference Line expression

Reference Line reference file

Reference Line expression



LIne type

Reference Line


Enter one or more point ID's and mathematical operators that can be evaluated.


Opens the Edit Expression window.


Opens a Popup menu to access point and expression features.

Reference Line Reference File



LIne type

Reference Line

Reference file

Fill in the following.


File ID

Name of the reference  file that contains the data



Opens a Select a File dialog box.


Column ID

Column in the group log table.



Opens the Select a Table/Column browser.

Auto update


Automatically update the line.



Keep the same historical information as a reference.

Reference Line Axes

Following is a description of reference line axes' behavior:

Expression reference lines default to use the chart's X-axis and Y-axis.

Reference file lines default to use their axes. They are named using the line ID with an _X and _Y suffix respectively. The axis configuration is based on the contents of the reference file. The X-axis defaults to no scroll.

More information

Option 4.2. Create a New Trend Chart Line (Overview of Detailed Method).