Create ranges of configurable durations

To guarantee that time ranges are always of the same length, configure time range overrides.

1. From the By Time list, select Time Range Override.

2. In the Relative Time field, type a PI relative time expression, as described in Understand relative time.

   PI AF creates a time range based on the end time supplied by the client application and the offset defined by the relative time.

   Note: You can use substitution parameters to read the relative time from the value of another attribute, as described in References to attribute values. If you do this, PI AF evaluates the referenced attribute value at the time of each data request.

Example

To create a one-hour rolling average, you would use the following settings:

• From the By Time list, select Time Range Override.

• In the Relative Time box, type -1h.

• From the By Time Range list, select Average.

With this configuration, the data reference always computes a 1-hour average, even when the client application specifies a different time range.