Span Lo

Span Hi and Span Lo apply to analog Parameters and Tags.Parameter Span Lo is normally left at a default value.  Parameter Span Lo 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 minimum value of  the tag or BLOCK:PARAMETER . 

Span Lo is used by some Scaling Types to "re-scale" the value read from the PLC.  For some Scale Types, Span Lo is the minimum value of the Tag.  For other Scale Types, SPANLO is for Display Use only.   For example, if No Scale is selected, the SPANLO appears on Trends and Displays, but is informational only.  The actual value can exceed Span Lo if no scale is used. (See Scaling Type for more details).

Span Lo is used by Trends, Overviews, and user built animation to determine the Minimum Value of the Tag.  For example, if a tank is filled by a Tag, the Span Lo is used to determine the tag' value for an empty Tank.

Range:                    -99,999,999,99 to 99,999,999,999
Field Type:            analog
Tag field:               .SPANLO