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 on the interface node. Values are sent to Data Archive if they exceed the specified deadband or have a timestamp that differs from the preceding value outside the bounds of the specified minimum or maximum, also known as the deadband. The deadband is defined by the specified deviation or percentage of the span. When exception values are stored, the preceding value is also stored, to accurately reflect the trend (the value and time stamp before the value fell outside the deadband).

For more information about exception reporting, refer to the following resources:

• To determine if your interface has implemented exception reporting that differs from standard UniInt, consult the interface documentation.

• For more information about exception reporting, see the PI Server System Management Guide. See PI Server System Management Guide.

• For recommendations about configuring exception reporting settings, see the OSIsoft Knowledge Base article What are recommended Exception and Compression settings.

The following attributes define the exception reporting settings:

• Minimum exception reporting interval

  Minimum frequency interval (excmin) value, in seconds. Using this value, the interface will not record values more frequently than the specified interval. If a value arrives before the specified time has elapsed, it is not sent to Data Archive.

• Maximum exception reporting interval

  Maximum frequency interval (excmax) value, in seconds. Using this value, the interface will write values to Data Archive no less frequently than the specified interval.

  Set excmax to 0 to disable exception reporting.

• Exception deviation

  The exception deviation, or deadband, value is stored in the excdev attribute, and specifies how much a value must differ from the previous value before it is considered to be a significant value.

  Set the exception deviation to a value, in engineering units, that is slightly smaller than the precision of the data source instrument.

• Exception deviation percentage

  The exception deviation percentage value is stored in the excdevpercent attribute, and specifies how much a value must differ from the previous value before it is considered to be a significant value, as a percentage of the span value.

The excdev attribute is related to excdevpercent attribute as shown in the equation: excdev = excdevpercent * span / 100. If either attribute is changed, the other is automatically updated to be compatible.