Understand time ranges for event frames and transfers

Event frames and transfers, by their nature, have a time range associated with them. When a calling application requests a value from an attribute, the value returned depends on the data reference and its configuration:

• When the calling application supplies no time context, PI AF calculates the attribute value using the time range of the event frame or transfer. For example, if an attribute contains a PI point configured with a time range summary option, the summary will be performed over the time range of the event frame or transfer.

• If an attribute contains a PI point configured with only the default time option, PI AF returns the value of the point at the end time of the event frame.

• When the calling application supplies a single timestamp, PI AF returns the value at the specified time, even if the time is outside the time range of the event frame or transfer.

• If the calling application supplies a time range, PI AF uses the intersection of the supplied time range and the time range of the event frame. If there is no intersection, a "No Data" event is returned.

• The shaded area in the following figure represents the intersection between an event frame time range and a requested time range. For attributes that contain a PI point configured with a time range summary option, the summary is performed over this intersection. If the attribute contains a PI point configured with only the default time option, the value at the start time of the intersection is returned.

  Intersection between event frame time range and requested time range