Configure data pairing for an XY plot

In an existing XY plot, use the Configure XY Plot pane to configure how AVEVA PI Vision retrieves data for each attribute and matches recorded values for paired attributes to create a data point.

Open the Configure XY Plot pane:

• When creating a new XY plot, add a second data item.

• For an existing plot, right-click the plot and then click Configure XY Plot.

Under Attributes, the pane lists a table of attributes. Each row lists an attribute that appears on the X-axis and the paired attributes on the Y-axis.

1. Select an X-axis row.

2. Under X Data Options, configure the X-axis attribute.

   • From the Data Retrieval list, select the method to retrieve X-axis attribute data:

     • Sampled

       Retrieve interpolated X-axis values for the specified time range in regular intervals. For example, if the time range is one hour and the Interval is set to 10m, then AVEVA PI Vision retrieves six values spaced 10 minutes apart. This option provides a way to retrieve evenly sampled data.

       Note: If you select this method, you must specify the sampling interval for your data. Enter a value in the Interval field and select a unit of time (second, minute, hour, day, week, month, or year).

     • Compressed

       Retrieve the actual values at their recorded times in Data Archive between the specified start and end time.

       Note: Compressed Data Retrieval is not available when you use a calculation for your X-axis.

     • Current Value

       Retrieve a single X-axis value at the current time of the display.

   • To configure the time range for the plot, select an option for the Start and End Times:

     • Display time range

       Use the time range for the overall display. XY plots configured with the Display time range option update when you change the display time.

     • Duration and Offset

       Set the length of time to show in the XY plot in seconds, minutes, hours, days, weeks, or months and the offset from the overall display's end time in seconds, minutes, hours, days, weeks, or months. XY plots configured with the Duration and Offset option update when you change the display time.

     • Use custom time range

       Set a custom start time and end time for the XY plot. Relative PI Time is also acceptable (Y, T, *,*, -8h, etc.). XY plots configured with the Use custom time range option do not update when you change the display time.

3. For each Y-axis attribute (listed under a separate Y Data Options section), configure the data pairing and data retrieval method.

   • Under Data Pairing to X, select the method to match this Y-axis attribute with the X-axis attribute:

     • Paired by timestamp

       AVEVA PI Vision finds Y-axis attribute values using the timestamp of each retrieved X-axis value.

     • Paired by position in the list

       AVEVA PI Vision retrieves Y-axis values independently of X-axis values and pairs the values by position in the list of values. (Y1 is paired with X1, Y2 is paired with X2, and so on.) This option allows you to specify different time ranges for X-axis and Y-axis values.

       Note:AVEVA PI Vision ignores Y-axis values in excess of the number of retrieved X-axis values.

   • From the Data Retrieval list, select the method to retrieve Y-axis attribute data. Available retrieval methods depend on the selected data-pairing method.

     Retrieval methods for data paired by timestamp:

     • Interpolated

       Retrieve interpolated Y-axis values at the same timestamp as each retrieved X-axis data point. X-axis and Y-axis values for each data point represent process measurements from the same point in time.

     • Exact time

       Retrieve only actual Y-axis values with the same timestamp as the X-axis values.

     • Exact time or previous value

       Retrieve Y-axis values with the same timestamp as the X-axis values. When a Y-axis value is unavailable at the X-axis timestamp, use the previous Y-axis value.

     • Exact time or next value

       Retrieve Y-axis values with the same timestamp as the X-axis values. When a Y-axis value is unavailable at the X-axis timestamp, use the next Y-axis value.

       Retrieval methods for data paired by position:

     • Sampled

       Retrieve interpolated Y-axis values for the specified time range in regular intervals. If you choose this method, you must specify the Interval period for sampling your data.

     • Compressed

       Retrieve the actual values stored between the specified start and end time.

       Note: Compressed Data Retrieval is not available when you use a calculation for your Y-axis

       For data paired by position, select the Override X Time Range check box to use a different time range. Enter the start and end times of the time range.