Appendix A
HMI Function Reference
A-20
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National Instruments Corporation
Decimate Historical Trend
Use the Decimate Historical Trend VI to take XY historical trend data, and decimate
(resample) it from the start timestamp to the stop timestamp. The decimated trend output
is a 1D array of the value at each time interval from the start timestamp to the stop
timestamp.
check start/stop time? determines whether the requested start and stop
times are checked against data available in the historical trends input. If
this value is TRUE, the start and stop timestamps are checked against the
first and last timestamp in the historical trend. A requested start/stop time
out of the range of the trend is not used—the first/last timestamp in the
trend is used.
historical trend is the historical trend to be decimated.
timestamp is the date and time for the value.
value is the value of the tag at the timestamp.
start timestamp is the timestamp at which the decimated trend starts. If
start timestamp is unwired, the decimated trend output starts at the first
timestamp in the historical trend.
stop timestamp is the desired stop time of the decimated trend. If stop
timestamp is unwired, the decimated trend output ends at or before the last
timestamp in the historical trend.
time interval determines the interval at which the trend is decimated or
resampled. If unwired, data is extracted with the default interval of
1 second.
decimated trend is a list of historical trend values starting at first
timestamp. Each trend value is time interval seconds apart.
first timestamp is the actual time associated with the first point in the
decimated trend.
last timestamp is the actual time associated with the last point in the
decimated trend.
