Span Hi Describes the intended maximum value of the tag. Depending on how the tag was built, this may be the true maximum or just an indication that maybe ignored.
Span Hi is used by some Scaling Types to "re-scale" the value read from the PLC. For some Scale Types, Span Hi is the maximum value of the Tag. For other, Scale Types, Span Hi is for display use only. For example, if No Scale is selected, the Span appears on Trends and Displays, but is informational only. The actual value can exceed Span Hi if no scale is used. (See Scaling Type for more details).
Span Hi is used by Trends, Overviews, and user built animation to determine the Maximum Value of the Tag. For example, if a tank is filled by a Tag, the Hi Span is used to determine the tag' value for a Full Tank. This field is for ANALOG tags and parameters only.
-99,999,999,99 to 99,999,999,999
Field Type: analog
Configuration: Span High
Tag field: .SPANHI