These options control how a tag’s value range (Y-axis values) are determined.
Y Min: The minimum value of the Y-Axis.
Y Max: The maximum value of the X-Axis.
Range Options: How value range is determined.
None: Y-axis range is determined by the Plot Min and Plot Max of the tag.
Current: Y-axis range is centered on the tag’s current value while keep the difference between the Plot Min and Plot Max.
Target: Y-axis range is centered first on the tag’s Target Limit, either the currently enabled limit or the specified Range Limit Type. If no Target limit is found, then the tag’s Box and Whisker Target is used. If neither target is found, the y-axis is centered on the tag’s current value. If both multiple targets are enabled, the Control Target Limit takes precedence.
Limit: Y-axis range is scaled so that the Plot Min and Max just above and below the tag’s Upper and Lower Limits. Only the most current limits are evaluated in this mode.
All Limits: Y-axis range is scaled so that the Plot Min and Max are just above and below the tag’s Upper and Lower Limits. All limits are evaluated in this mode, so the Plot Max is just above the Upper Limit with the greatest value, and the Plot Min is just below the Lower Limit with the lowest value.
Limit SIGMA: The Trend first evaluates the difference between the Target Limit and the Upper Limit of the tag, and then adds a third of that value to the Upper Limit to get the Plot Max. The same logic applies in calculating the Plot Min.
Range Limit Type: Which limit type to use for the Limit and Target range options, if applicable.
Auto Scale: Changes Y-Axis scale based on minimum and maximum values in the trend. This can also be toggled in the Tag Info Grid Right-Click Menu.
Y-Axis Rounding: When Auto Scale is enabled, the Trend will select a Plot Min and Max that nicely accommodate the value range spatially. In the example below, Y-Axis rounding is not enabled on the top trend and enabled on the bottom trend. Regardless of the Auto Scale or Y-Axis Rounding settings, the Trend will try to limit the number of decimals in the Y-Axis label values.
