Basic Historical Data Management begins with the Engine trend extension. Each Engine attribute that can be trended can store historical data samples about the attribute. Sample storage in the Engine is limited to the size of the individual Trend Buffer. For storage of long-term or large numbers of samples, configure your system to store historical data in the Metasys server . Use the Trend Extension to view and configure trends in the Engine and the Trend Study to view trend data from the Engine and/or Metasys server .
Note: Although multiple trend extensions can be added to an object on an NxE, these extensions will be combined as a single trend if sent to a Historical Data Repository. This may not yield the expected result. To use multiple trends on a single object in an Historical Data Repository, create duplicate AV or BV objects and that map to the point in question, then create a new trend on the parallel AV or BV.