Single and multiple scales for the vertical axis – Rockwell Automation FactoryTalk Historian SE ProcessBook 3.2 User Guide User Manual
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Autorange scale
The value scale is determined by a calculation based on minimum and
maximum values in the trend. As new data are received from the
server, the high and low values may change, and the scale is
recalculated accordingly.
For example, if the original scale ranged from 5 to 100, but the new
data has a high of 103, then the new plot shows a range from 5 to
105 (the nearest number divisible by 5 and larger than the high
value).
If more than one tag is plotted on a single scale, the value scale is
calculated from the highest and lowest values for all the tags.
Database scale
If the scale is set to Database, the range is the same as the limits for
the point on the server. The minimum value is termed zero, and the
maximum value is the sum of the zero value plus the span value.
For example, suppose the tag attributes for a point are Zero = 3 and
Span = 6. The plot range therefore is based on making the minimum
and maximum values 3 to 9.
Logarithmic scale
If you prefer a logarithmic scale, check this option. This option is
disabled for digital, string, time stamp, or integer tags.
Manually Defined
scale
When the scale is configured, an arbitrary minimum and maximum
scale value may be entered.
Single and Multiple Scales for the Vertical Axis
Value scales are labeled whenever there is enough room. Configure these
labels with either single or multiple scales.
For a single scale label, the union of the ranges for all traces appears.
For multiple scale labels, the range for the first trace appears next to
the value axis. Ranges for the other traces appear in increasing
distance from the axis in the order the tags are listed in the trend
legend.
On a single scale trend, traces that contain only one value (a flat line) or have
no data are governed by special scaling rules. When a trend is composed of only
flat or no data traces, the default value scale range is inflated to prevent showing a