Quality mapping

Data quality information can be included when writing time-series data to the Data Archive. This feature is exposed by the PI Web API using a quality mapping.

A quality mapping defines the relationship between OMF values and an associated data quality. The PI Web API creates several default quality mappings as part of the installation process. Quality mappings are stored in the OMF Asset Framework database as AF Enumeration Sets. All quality mapping enumeration set names begin with the prefix __qualitymap., and the remainder of the name is the ID of the quality mapping.

The following is an example dynamic type that utilizes the quality mapping feature:

{

"id": "Quality-Mapping-Example",

"type": "object",

"classification": "dynamic",

"metadata": {

"DataQualitySchema": "OPCUA"

},

"properties": {

"Time": {

"type": "string",

"format": "date-time",

"isindex": true

},

"Mode": {

"type": "Number",

"format": "float32"

},

"Status": {

"type": "Integer",

"format": "uint32",

"isquality": true

}

}

}

In the example above, we utilize the OPC UA quality mapping (stored in AF as __qualitymap.OPCUA). To associate the dynamic type with this quality mapping, a property with the isquality keyword must be set to true, and the quality mapping ID must be declared using the DataQualitySchema metadata key-value pair.

Note: The quality property, as displayed in the Status section of the example above, must use the identical type and format defined in the DataQualitySchema.

For more information on how quality mappings are constructed, see the detailed changes in the PI Web API Reference.