Retrieve data

When the DisplayChart() method is called, the SPC Chart control retrieves the specified characteristic's sample results that match the specified filter criteria. The retrieved data is sorted by the requested_time_utc column of the sample table.

The SPC Chart control checks the MES database for new samples at an interval defined in the RefreshRate property.

If one or more results are added to any samples that match the filter criteria since the last check, the SPC Chart is updated. If the number of points on the chart is equal to the configured value of the NumberOfPointsFilter property, the control does the following:

• Deletes the first point

• Adds the new point

• Replots the chart

If new results are added to an existing sample, the control recalculates the point and replots the chart.

The chart is also updated when other events related to chart data occur, such as sample data being updated, marking a data point to be ignored or as a control move, or adding a note to a data point.