Span Hi and Span Lo apply to analog Parameters and Tags. Parameter Span Hi and Low are normally left at a default value. Parameter Span Hi can save time and typing or enforce a standard if this parameter will be used in a predictable way to create Tags or Blocks. This value appears on displays, trend and dialog boxes describing the maximum value of the tag or BLOCK:PARAMETER built using this parameter.
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 Lo 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.
-99,999,999,99 to 99,999,999,999
Field Type: analog
Tag field: .SPANHI