Rockwell Automation 9301 Series RSView32 Users Guide - Manual (Page 501)

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RSView32 User’s Guide
How the trend control tags work
When a trend is running, the data for a trend—either real-time or
historical—is stored in a buffer. The trend is a view of this buffer. The
values of the control tags determine how the data is viewed. The
following illustration shows what the OldestTime, TimeRange,
StartTime, and NewestTime control tags represent:
When the value of one control tag changes, some aspect of this view
changes. For example, the TimeRange tag determines how much of
the data is shown at one time and the StartTime determines where the
right margin of the trend is in relation to the total time span
represented by the data.
\YMag Magnification of the vertical axis in percent.
0No magnification
100Twice the resolution (half the range)
-100Half the resolution (twice the range)
Read and write
\YOffset Offset of the vertical axis in percent. Moves the view up
or down but does not change the time range. Read and write
Tag name Function Read or Write?
OldestTime TimeRange
StartTim
e
NewestTime StartTime
OldestTime TimeRange NewestTime