Rockwell Automation FactoryTalk Historian SE DataLink 4.2 User Guide - Manual (Page 30)

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FactoryTalk Historian DataLink User Guide
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 To enter intervals in terms of frequency, convert the frequency to
equivalent seconds. For example, a frequency of 25 Hz should be
entered as a 0.04s interval (=1/25 of a second).
 When using relative formats (for example, -2h), the reference time
used to translate the time format is different for function start and end
times. The current wall clock time is the reference for a relative start
time, but the start time is then used as the reference for a relative end
time.
FactoryTalk Historian DataLink supports only the default 1900 date system
supported by Excel. FactoryTalk Historian DataLink does not support Excel's 1904
date system, and returns incorrect time stamps if this system is used.
Appended Data
Time stamps are particularly relevant to FactoryTalk Historian point
events. Each event value is accompanied by a time stamp that gives it
context.
Most FactoryTalk Historian DataLink functions can return corresponding
time stamp values and other point data with FactoryTalk Historian event or
calculated expression values. These data can be appended to values
returned in a FactoryTalk Historian function array, and include:
 Event time stamps.
 Time stamps indicating start and end times of an interval.
 Time stamps indicating the occurrence of minimum and maximum
values.
 The percentage of good values over a sampling interval.
 Value attributes.
 Manually entered event annotations.
 Source FactoryTalk Historian server names.