Change the trend configuration at run time

If you select the Allow runtime changes option when you configure your historical trend, operators can configure a historical trend while it is running. Operators configure the trend from a dialog box that appears after selecting the trend from a displayed window.

Configure a historical trend during run time

1. Select the historical trend while it is running. The Historical Trend Setup dialog box appears.

   

2. In the Chart Start area, type the starting date and time of the historical trend data collection interval.

3. In the Display Mode area, select the type of historical trend chart.

   The trend display mode affects performance. The primary factor that determines trend performance is the length of the lines shown in a trend. The longer the lines, the longer it takes to generate the trend.

   Line width also affects performance. Wide lines take significantly longer to draw. Min/Max or Average/Scatter trends can be created more quickly than an Average/Bar Chart.

4. In the Chart Length area, type the duration to be displayed on the trend and then select the unit of measure.

   For example, if you enter 2 and select Hrs, the trend duration is 2 hours.

5. In the Chart Range area, type the percentage of engineering unit range shown on the vertical axis of the historical trend.

   The scale of the trend is a segment of the trended tag’s engineering unit range defined by a percentage range. The values range from 0 to 100. For example, if you want to trend the variance of the selected tags from 40 to 60 percent of their engineering unit range, type 40 and 60 in the Min and Max range boxes, respectively.

6. In the Tags area, select a pen number to assign a tag.

   The Select Tags dialog box appears with a list of tags that can be assigned to the historical trend pen.

7. Use the following statement in a QuickScript or button to allow the operator to update the chart:

   Hist_TrendTag.UpdateTrend = 1;

8. Use any of the following functions in a QuickScript or on a button:

   HTUpdateToCurrentTime(Hist_Tag);

   HTScrollLeft(Hist_Tag,Percent);

   HTScrollRight(Hist_Tag,Percent);

   HTZoomIn(Hist_Tag,LockString);

   HTZoomOut(Hist_Tag,LockString);

   HTSetPenName(Hist_Tag,PenNum,Tagname);

   For more information about using scripts containing trend functions, see Control a historical trend wizard using scripts.

9. Change any of the following trend tag dotfields:

   .ChartStart

   .ChartLength

   .MaxRange

   .MinRange

   .Pen1-.Pen8

   For more information about using dotfields with historical trends, see Control a historical trend using dotfields.