SetInitialValue

The SetInitialValue function sets the value of a specific data point before the query range begins.

It's part of the HistoryFill class, and is used to provide boundary-filling functionality to ARDI drivers.

Industrial historians and high-quality time-series databases will often ensure that you get 'bounding values' around the time-range you request. For example, if you query data between 9:12 and 9:50, you'll get values at those times even if there weren't recordings at those exact times.

ARDI expects this behaviour from drivers, where possible. It's one of the reasons we suggest you avoid using relational databases for time-series information, as this step is time-consuming and computationally expensive.

For systems that don't natively extract boundary data in a single query, the SetInitialValue command allows you to set the starting values for each of the points with a distinct query.

For example….

#We have loaded an array of values from before the requested range, 
#  in an array of 'Point Name' => 'Value' pairs...
for d in dta:
   history.SetInitialValue(d,dta[d])