Display data quality

A PI Tag represents a single value datum, so it cannot display both a value and a AVEVA Enterprise SCADA-style data quality.

Each sample of a PI Tag can show either the digital value or the AVEVA Enterprise SCADA-style data quality. The flags structure in the RealTime Database (RTDB) stores data quality for RTDB points. The configuration file pioasys_cfg.dat contains information on handling data quality fields within the flags structure. For example: which data quality fields should be inspected, which data quality fields are good and which are bad. When the PI-OASyS interface is started, the configuration file is parsed, and the data quality information is stored in the internal storage for Data Quality (DQ) checking.

Notes: For a Data Quality Tag appropriate digital states (digital set) that represent the data quality should be created in the PI Server prior to the creation of the DQ tag. The digital set has a strong relationship with the fields in the flags structure. It is based on a set of virtual bit states with each bit representing a field in the flags. Only the relevant data quality combinations will be set in the digital set. The PI-OASyS interface will check all the DQ fields in the order of the listed fields in the [DQTAG] section of the configuration file. The digital states in the digital set should be in the same order.

If you require a timestamped record for both the value and quality of a point, then two PI Tags must be created.