Data Group
The following describes the historical data group settings specific to the OPC HDA Historical Values connector.
The following Group Types are available:
Summary Values from Server retrieves summary calculations directly from the historian. Consult the historian documentation from the OPC HDA server vendor to see what calculations are supported.
Summary Values from XLReporter retrieves sampled values from the historian and performs calculations on those samples for reporting.
Raw Values retrieves values logged to the historian between the start and end time specified.
Note
By default, summary values are time-weighted calculations and values are propagated based on the last known value. However, to change this so that summary values are calculated strictly on the data returned check use raw values.
Group Settings
For Summary Values from XLReporter groups, the Retrieval settings define how data is retrieved for the calculations selected for the group. The following settings are available:
Retrieval Mode defines how data is retrieved from the historian. Both Sampled Values and Raw Values are available where Sampled Values uses the Interpolated calculation. Note, if the OPC HDA server does not support the Interpolated calculation, do not use Sampled Values.
Rate is the interval (in seconds) that sampled values are retrieved from the historian.
Lead Time is the amount of time (in seconds) to retrieve data before the start time.