Interface status events

The PI to PI interface may update a tag to indicate a specific status event. These status events represent data that is generated by the interface and therefore will not exist for the source tag. Three specific status events can be generated by the interface:

• IO Timeout status events are triggered when the interface loses a PI Server connection. This information informs users that current data is not being collected. An event is written to indicate the time of disconnection and another event is written to indicate the time of reconnection.

  Note: When UniInt interface failover is configured, the interface will suppress writing IO Timeout to its PI Points. If the interface did write IO Timeout then when the backup interface transitions to primary, it won't able to send data older than the IO Timeout event.

• Access Denied status events are written whenever the interface is denied access to a tag’s data or attribute information.

• Intf Shut status events are enabled through /stopstat startup parameter. When enabled an event is written when the interface is stopped and again on startup. These events tell users that no data is being collected because the interface is not running. See a more detailed description in the General interface operation parameters section.

To prevent a data mismatch between PI Servers these status events should be disabled. If enabled, these events create a data gap that will not be filled through history recovery.

Each tag receives an IO Timeout event at the time of PI Server disconnection and a second event at reconnection. Likewise, when the interface is stopped and started a 'Shutdown' event is written to each tag. History recovery begins either at the start of the recovery period or a tag's current value, whichever is more recent. The status events are updated prior to performing history recovery, making them the starting point of the recovery period for each tag. This results in a gap in data for a time period that might otherwise be recovered.

Interface status events are configured on a tag-by-tag basis through the Location3 tag attribute. Interface shutdown events are enabled through the interface startup script. By default shutdown events are not written by the interface.

Note: See the Learn about command line parameters topic for additional information about the potential for data mismatches. In particular read the /sn parameter description; and also see AVEVA Knowledge Base article: KB00869 - Considerations for exact data match in source and target PI Servers using the PI to PI Interface.