Learn about start and end trigger conditions

An event frame generation analysis starts an event frame when the start trigger condition evaluates to true. Because a random spike in an input value can make the condition true, noisy data can lead to the creation of many unwanted event frames. To counter the effects of data spikes, you can set a time interval before starting an event frame by entering a value in the True for field.

When a start trigger condition changes to true, the True for value determines how long to wait to evaluate again; if it is still true, an event frame is started. While the start trigger behavior for event frames is based on the True for setting, it works differently for analyses assigned to periodic scheduling.

Periodic scheduling

With periodic scheduling, analyses only evaluate at the specified time in the schedule irrespective of the True for setting. True for evaluations will be the first periodic evaluation following the end of True for period. Any values that were not captured on periodic schedule evaluations will not be considered.

Depending on how you configure the periodic schedule, there may not be any evaluation within the True for period. If you want to ensure that the analysis evaluates within that time frame, you may do so by setting the periodic schedule to be shorter than the True for value (for example, evaluate every minute and a True for 5 minutes) or opt for event-triggered scheduling.

If you want the analysis to evaluate right at the end of the True for period, set the True for to fall on the periodic schedule -- for example, every 3 minutes with a True for value of 9 minutes -- or choose event-triggered scheduling.

Event-triggered scheduling

With event-triggered scheduling, when a start trigger condition changes to true, the True for value determines how long to wait to evaluate it again; if it is still true, an event frame is started. The analysis will evaluate every time the value of the triggering input attribute updates. Configuring the analysis to be event-triggered and having it triggered off of every input attribute in the start trigger condition can prevent the analysis from missing evaluations.

The start time for the event frame is the time that the start trigger condition first evaluated to true. The True for value has no effect on the start or end time of the event frame.

The event frame will close when the start trigger condition is false. Configuring an end trigger is optional. If both the start and end trigger conditions are configured, the event frame will end when the end trigger condition is met. This is regardless of whether the start trigger condition still holds true.

Tip: If using both start and end triggers, make sure the expressions never evaluate to TRUE at the same time since this may lead to event frames with zero-second durations. We recommend that you configure event frames to use only a start trigger expression.