Tag scale

The scale is the minimum and maximum range of values for the tag. Each tag has its own scale, which is usually quite different from other tags in the chart. Scales for tags on the chart are always displayed along the value axis.

Only discrete, analog, and summary tags can be scaled; event and string tags cannot be scaled. For discrete tags, the message associated with the 1 value is used as the maximum scale value, and the message associated with the 0 value is used as the minimum scale value.

In the following chart, two tags are trended in stacked mode. The scale for the ReactLevel tag is from 0 to 3000. The scale for the other tag, ReactTemp, is from 0 to 220.

The minimum and maximum values of each scale appear on the value axis.

The initial scale of a tag is determined by its Min/Max EU settings in the Historian. To adjust tag scales, you have two options:

• Edit the value axis range individually for each tag. For more information, see Configure trend options for a tag.

• Use the scaling commands to adjust the scale of single tag or all tags. For more information, see Scale tags up or down and subsequent sections.

You can also change the way in which scale values appear on the value axis. The following sections describe the available options.