Subclause 5.4.3.3 deals with Aggregate specific characteristics and behaviour that is specific to a particular Aggregate.
Each subclause has a table which formally expresses the Aggregate behaviour (including any exceptions). The meaning of each of the fields in the table is described in Table 14.
Description of Table 14:
- The first column is the common name for the item.
- The second column includes a description of the item and a list of the valid selections with for the item including a description of each selection.
- The second part of the table describes how the status associated with the Aggregate calculation is computed.
- The last part of the table lists what behaviour is expected from the Aggregate for some common special cases. These behaviours require text descriptions so there is no list of valid selections.
Table 14 – Aggregate table description
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Aggregate Characteristics |
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Type |
The type of Aggregate. <Interpolated | Calculated | Raw>
Interpolated: See definition for Interpolated. Calculated: Computed from defined calculation. Raw: Selects a raw value from within an interval. |
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Data Type |
The data type of the result. <Double | Int32 | Same as Source> |
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Use Bounds |
How the Aggregate deals with bounds. <None | Interpolated | Simple>
None: Bounds do not apply to the Aggregate. Interpolated: Uses Interpolated Bounds. Simple: Uses Simple Bounds. |
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Timestamp |
What is the time stamp of the resulting Aggregate value:
startTime: The time at the start of the interval. endTime: The time at the end of the interval. Raw: The time associated with a value in the interval. |
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StatusCode Calculations |
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Calculation Method |
How the status code is calculated: <PercentValues | PercentTime | Custom>
PercentValues: Based on percentage of value counts. PercentTime: Based on percentage of time interval. Custom: Specific to the Aggregate (description included). |
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Partial |
For partial intervals does the Aggregate set this bit <Set Sometimes | Not Set>
It may also describe any special cases for setting this bit |
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Calculated |
Describes the usage of the calculated bit. <Set Always | Set Sometimes | Not Set>
Set Always: The bit is always set. Set Sometimes: The bit is sometimes set (describes when). Not Set: The bit is never set. |
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Interpolated |
Describes the usage of the interpolated bit. <Set Always | Set Sometimes | Not Set>
Set Always: The bit is always set. Set Sometimes: The bit is sometimes set (describes when). Not Set: The bit is never set. |
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Raw |
Describes the usage of the Raw bit. <Set Always | Set Sometimes | Not Set>
Set Always: The bit is always set. Set Sometimes: The bit is sometimes set (describes when). Not Set: The bit is never set. |
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Multi Value |
Describes the usage of the multi value bit. <Set Sometimes | Not Set>
Set Sometimes: The bit is used (see OPC 10000-11). Not Set: The bit is never set. |
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StatusCode Common Special Cases |
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Before Start of Data |
If the entire interval is before the start of data. |
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After End of Data |
If the entire interval is after the end of data (as determined by the Historian). |
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Start Bound Not Found |
If the starting bound is not found for the earliest interval and it is not partial, then what, if any, special processing should be done. |
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End Bound Not Found |
If the ending bound is not found for the latest interval and it is not partial, then what, if any, special processing should be done. |
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Bound Bad |
If the Bounding value is Bad, then what, if any, special processing should be done. |
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Bound Uncertain |
If the Bounding value is uncertain, then what, if any, special processing should be done. |