What is a graph?

Definition

A graph is a graphical chart showing the values or states of up to ten IGSS objects. All values and states from the object types analog, table, digital and counter can be displayed in a graph. The data source can be either log files (*.log) or base class files (*.bcl).

Use

Use a graph to achieve the following:

a graphical overview of the values and states of one or more process components
detect adverse trends at an early stage
monitor the effect of interventions by combining historical graph data with current process values

Three types of graphs

There are three types of graphs:

A predefined graph is a graph defined by the system designer which the operator can access from the Graph menu or by clicking on a symbol representing the graph. Most of the graph properties cannot be changed by the operator during supervision, but he can change certain layout properties.
An dynamic graph is a graph created on-the-fly by the operator during supervision. The operator simply selects the IGSS objects to include in the graph and then selects Graph ® Create Dynamic Graph. This function is very useful, if the operator wants to monitor a specific process component before and after an intervention. A dynamic graph can be saved as a user-defined graph (*.usr). When re-opened, the graph will be dynamically updated.
A static graph is a snapshot of a predefined or a dynamic graph that the operator wants to save for documentation purposes. A static graph can be saved as a graph file (*.gph). When re-opened, the graph can be shown, but not updated.

For information on the two last types of graphs, refer to the Help function of IGSS Supervise.

Graph menu

The Graph menu shows all available graphs in the active area provided that the Name to Menu option is selected for each graph. A checkmark beside the graph name means that it is open.

Graph properties

When you create a graph, you specify a number of properties from the New Graph Properties and Define Graph Parameters dialog boxes. The properties can be changed at any time in IGSS Definition. The most important properties are:

This property …	Allows you to …
Window elements	specify which graph window elements you want the operator to see, for example, title bar, minimize and maximize buttons, etc.
Name to Menu	show the graph name in the Graph menu to facilitate easy access for the operator.
Grid	show a grid background in the graph window which makes it easier to read values.
Horizontal Scroll Bar	navigate through the selected time period using a scroll bar.
Autostart	start the graph drawing immediately when the graph is selected.
Start offset	specify an offset from the current time, for example, to show values from 1 hour back in time.
Source	specify whether you want to base graph values on the LOG or BCL files.

For an explanation of the remaining properties, open the New Graph Properties or Define Graph Parameters dialog box, click the $images\ico_help.gif$ in the upper right hand corner of the dialog box, then click the item you want information about.