DataHub^® APIs for C++, Java, and .NET : Version 7.2
	Chapter 3. Standard Java Applets

DataHubTrend

DataHubTrend — a dynamically updating graphical display of DataHub values.

Description

This applet displays the values of several DataHub points in a dynamically updating graphical display.

Base Class

DataHubListener

Parameters

Parameter	Type	Default	Description
`maxpoints`	`int`	`0`	The maximum number of points per trace to display. This determines the amount of data in the trace, which will have an effect on CPU usage. Do not set both `maxpoints` and `maxtime`.
`maxtime`	`double`	`20`	The number of seconds worth of data per trace to display. This determines the amount of data in the trace, which will have an effect on CPU usage. Do not set both `maxtime` and `maxpoints`.
`refreshrate`	`int`	`100`	The refresh rate of the display, in milliseconds.
`min`	`double`	`0`	The Y-axis minimum.
`max`	`double`	`100`	The Y-axis maximum. (Note that the X-axis span is automatically determined by the minimum and maximum time stamps for all of the traces in the trend.)
`pointN`	N/A	none	Specifies which DataHub point to plot, as well as the color and shape of the trace. You can plot a maximum of 10 traces. See below for details.

The `pointN` parameter

You will need to specify a pointN parameter for each trace in the trend, as follows:

Syntax

<param name="pointN" value="pointname;color;flags">

Name and Value

pointN

The first trace must be named point1, the second trace point2, the third point3 and so on up to point10.

pointname

The name of a DataHub point, without the domain name.

color

A color, specified as #000000.

flags

(optional) One of: extend, square, or extend|square where:

extend: The trace for this point will be automatically extended horizontally on each update of the other traces in the trend graph.
square: The trace will be drawn as a step function instead of drawing a straight line from one value to the next.

Example

<param name="point1" value="PID1.Mv;#ff9900">
<param name="point2" value="PID1.Sp;#0000ff;extend|square">
<param name="point3" value="PID1.Pv;#009900">


DataHubToggleButton		DataHubViewer