During auto-run sequences, the software will arm, capture and transfer data continuously until it receives a HALT command from a plug-in or auto-search or the user presses the halt button. This allows plug-ins and auto-searches to act as soft triggers. They can look for conditions that can not be detected with the hardware trigger circuits (like protocol level events or duration measurements beyond the hardware timer limits) and halt the acquisition so that the interesting event is visible on the screen.
It is important to understand that although soft triggers can 'trigger' on very high level, complicated events, they differ from hardware triggers in that they are not guaranteed to capture one-time/infrequent events. They capture a buffer of data and analyze it. If the buffer does not contain the trigger condition, another buffer is captured and analyzed until the trigger condition is found. This means that the target activity that occurs between fetches is never seen. However, if the trigger condition is repetitive, you will eventually catch it. The auto-run sequence combined with an auto-search or a plug-in using the HALT control code, allows you to start DigiView capturing and walk away. If it ever captures your soft trigger condition, it will halt on that capture so that it is on the screen when you return.