Exception reporting and compression testing

The PI approach to exception reporting and compression testing is not modified for AVEVA Enterprise SCADA.

Exception Reporting and Compression Testing are features provided by PI for the purposes of performance fine-tuning. The configuration of these features will impact the data flow from the PI-OASyS interface node to the PI server for the points configured.

The Exception Reporting feature utilizes a deadband to refine data in order to reduce the data transfer load between the PI-OASyS interface and the PI server. The Compression Testing feature is performed by the PI Snapshot Subsystem on the PI server to enhance data storage and improve overall disk space consumption.

Notes: When a point is configured for Exception Reporting, its incoming point values are compared until a new value exceeds the deadband, in which case the new value and its timestamp along with the previous value and timestamp will be sent as snapshot to PI server.

For PI-OASyS interface, if a PI tag is configured using PubSub, we suggest turning off the exception because the interface already does the data collection by exception through PubSub.

For a detailed description of how these functions work, please refer to the Exception Reporting and Compression Testing section of the PI Server 2012 System Management Guide, available from OSISoft.