A.4.3.3 Quality

The Quality of a Data Value in the OPC UA Server is represented as a StatusCode.

The COM UA Proxy maps the Severity, Subcode and the limit bits of the OPC UA Status code to the lower 8 bits of the OPC DA Quality structure (of the form QQSSSSLL). Figure A.18 illustrates this mapping.

Figure A.18 – OPC UA Status Code to OPC DA quality mapping

The Severity field of the Status code is mapped to the primary quality. The SubCode is mapped to the Sub Status and the Limit Bits are mapped to the Limit field.

Table A.7 shows a mapping of the OPC UA status code to OPC DA primary quality

Table A.7 – Quality mapping
OPC UA Status Code OPC DA Primary Quality (Quality & Sub status QQSSSS)
GoodGOOD
Good_LocalOverrideLOCAL_OVERRIDE
UncertainUNCERTAIN
Uncertain_SubNormalSUB_NORMAL
Uncertain_SensorNotAccurateSENSOR_CAL
Uncertain_EngineeringUnitsExceededEGU_EXCEEDED
Uncertain_LastUsableValueLAST_USABLE
BadBAD
Bad_ConfigurationErrorCONFIG_ERROR
Bad_NotConnectedNOT_CONNECTED
Bad_NoCommunicationCOMM_FAILURE
Bad_OutOfServiceOUT_OF_SERVICE
Bad_DeviceFailureDEVICE_FAILURE
Bad_SensorFailureSENSOR_FAILURE
Bad_WaitingForInitialDataWAITING_FOR_INITIAL_DATA