Exception reporting attributes

To minimize the data that is stored and transmitted over the network, you can use exception reporting to filter out value changes that are not meaningful. Filtering takes place at the interface node before data is sent to Data Archive.

• Maximum exception reporting interval (excmax)

  This attribute configures the maximum time period allowed between sending values to Data Archive.

  This setting applies to both advise and polled tags. For advise tags, if PI Interface for OPC DA does not receive a value after the specified number of seconds and does not detect a dropped connection, it sends the last value received to the Data Archive with the time stamp set to the last time stamp plus excmax time. For polled tags, the interface sends a value to Data Archive if it has not sent one in the last excmax seconds, even if the new value does not pass excdev tests.

• Minimum exception reporting interval (excmin)

  This attribute configures the minimum time period between values sent to Data Archive.

• Exception deviation (excdev)

  This attribute configures the minimum change from the last value sent to Data Archive required for PI Interface for OPC DA to send a new value.

Users can disable exception handling altogether for a given point by setting ExcMax=0. For advise points in particular, this setting prevents the interface from re-sending old data with a new timestamp.

For more detailed information about ExcMax for advise tags, see Appendix A. Set ExcMax on advise and event points.