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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.6 illustrates this mapping.

image012.png

Figure A.6 – 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)

Good

GOOD

Good_LocalOverride

LOCAL_OVERRIDE

Uncertain

UNCERTAIN

Uncertain_SubNormal

SUB_NORMAL

Uncertain_SensorNotAccurate

SENSOR_CAL

Uncertain_EngineeringUnitsExceeded

EGU_EXCEEDED

Uncertain_LastUsableValue

LAST_USABLE

Bad

BAD

Bad_ConfigurationError

CONFIG_ERROR

Bad_NotConnected

NOT_CONNECTED

Bad_NoCommunication

COMM_FAILURE

Bad_OutOfService

OUT_OF_SERVICE

Bad_DeviceFailure

DEVICE_FAILURE

Bad_SensorFailure

SENSOR_FAILURE

Bad_WaitingForInitialData

WAITING_FOR_INITIAL_DATA

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