Scale tags automatically

When a tag is automatically scaled, the value axis range is automatically adjusted to reflect the actual data currently being displayed for the trend. For example, if the default value axis range is 0 to 3000, and the data ranged from 1827 to 2059, the scale might be automatically adjusted to a range of 1800 to 2100.

The adjusted scale does not exactly match the actual minimum and maximum data values for the chart. The calculation rounds the values so as to make the chart easier to read. Also, a percentage allocation is added to the final values so that the adjusted scale fits within the boundaries of the trend chart. Therefore, the adjusted scale is a round number slightly above the actual data values.

You can automatically scale a single tag or all of the tags in a trend. For information on resetting scales back to the original default, see Return tags to their original scale.

Tag scaling is performed automatically for a trend while it is retrieving live data. If the trended data includes points outside of the scale region, any affected tags are scaled automatically.

To automatically scale a single tag

1. Select a tag from the tag list.

2. From the Chart menu, in the Single Tag Scale group, click Auto.

To automatically scale all tags

• From the Chart menu, in the All Tags Scale group, click Auto.

The following example shows a tag automatically scaled: