In OPC UA Aggregates the StatusCode is used to indicate the conditions under which a value or Event was stored, and thereby can be used as an indicator of its usability. Due to the nature of aggregated data, additional information beyond the basic quality and call result code needs to be conveyed to the client. For example, whether or not the result was Interpolated, were all data inputs to a calculation of Good quality, etc.
In the following, Table 8 contains codes with Bad severity indicating a failure; Table 9 contains codes with Uncertain severity indicating that the value has been retrieved under sub-normal conditions. It is important to note, that these are the codes that are specific for OPC UA Aggregates and that they supplement the codes that apply to all types of data; they are therefore defined in OPC 10000-4, OPC 10000-8 and OPC 10000-11.
Table 8 – Bad operation level result codes
|Bad_AggregateListMismatch||The requested number of Aggregates does not match the requested number of NodeIds. When multiple Aggregates are requested, a corresponding NodeId is required for each AggregateFunction.|
|Bad_AggregateNotSupported||The requested AggregateFunction is not supported by the Server for the specified Node.|
|Bad_AggregateInvalidInputs||The Aggregate value could not be derived due to invalid data inputs, errors attempting to perform data conversions or similar situations.|
Table 9 – Uncertain operation level result codes
|Uncertain_DataSubNormal||The value is derived from raw values and has less than the required number of Good values.|