Rockwell Automation FactoryTalk Historian SE DataLink 4.2 User Guide - Manual (Page 43)

3
●
FactoryTalk Historian DataLink Functions
●
●
●
●
●
35
Retrieval Mode One of five modes can be selected to produce an archive value:
 Previous
Retrieves the value exactly matching or preceding the specified
time stamp.
 Previous only
Retrieves the value preceding the specified time stamp.
 Interpolated
Interpolates the value at the specified time, or follows Previous
only behavior.
 Auto
Interpolates the value at the specified time, or follows Previous
behavior.

Next
Retrieves the value exactly matching or following the specified
time stamp.
 Next Only
Retrieves the value following the specified time stamp.

Exact Time
Retrieves only a value exactly matching the time stamp, or returns
No events found if no value exists.
Special Notes Reference a range of cells containing tag names to display archived
values for each.
For tags with step attributes, Previous and Previous only modes are
substituted for Auto and Interpolated calculation modes, respectively.
PIExpVal() is used if an expression is substituted for a tag; otherwise
PIArcVal() is used.
Example:
To see the value of the sinusoid tag corresponding to a specific time, the
following arguments are set for the Archive Value function:
Tagname = sinusoid
Timestamp = 30-Sep-07 15:13
Retrieval Mode = previous
time at left