HistoryValueHistoryValue — a single value from the Historian, consisting of value, x-axis and
quality.
class HistoryValue
{
xaxis;
value;
quality;
}
xaxisThe X axis value, generally the time stamp in UNIX time for this value. In some cases, a query can return an Y-vs-X result set instead of a Y-vs-Time result set. Consequently the X axis may not be time in all cases. This is a floating point number that can represent fractional seconds.
valueThe data value. This is either a calculated value or a raw value, depending on the type of query.
qualityThe quality of this sample. For raw samples this is an OPC DA2
item quality. For computed samples this is GOOD,
BAD or another more precise
BAD quality (such as DEVICE
FAILURE) taken from the qualities of the raw values
used in the computation.
None.