Main Content

OPC HDA Quality Values

OPC HDA quality values identify the quality or integrity of retrieved historical data. The quality is returned as a 32-bit number with only the upper 16 bits relating specifically to HDA; the lower 16 bits relate to both OPC data access. For information on data access quality, see OPC Quality.

Upper 16-bit HDA Quality Values

Quality Values DescriptionMask ValueAssociated DA Quality
OPCHDA_EXTRADATAMore than one piece of data that might be hidden exists at same timestamp. 0x00010000 Good, Bad, Quest
OPCHDA_INTERPOLATEDInterpolated data value. 0x00020000Good, Bad, Quest
OPCHDA_RAWRaw data value. 0x00040000Good, Bad, Quest
OPCHDA_CALCULATEDCalculated data value, as would be returned from a ReadProcessed call. 0x00080000Good, Bad, Quest
OPCHDA_NOBOUNDNo data found to provide upper or lower bound value. 0x00100000Bad
OPCHDA_NODATANo data collected. Archiving not active (for item or all items). 0x00200000Bad
OPCHDA_DATALOSTCollection started / stopped / lost. 0x00400000Bad
OPCHDA_CONVERSIONScaling / conversion error. 0x00800000Bad, Quest
OPCHDA_PARTIALAggregate value is for an incomplete interval. 0x01000000Good, Bad, Quest