Independent Queues

As stated previously, the callback and the queuing mechanisms operate totally independently of each other, so VISA keeps the information for event occurrences separately for both mechanisms. Therefore, VISA maintains the suspended handler queue separately from the event queue used for the queuing mechanism. The VI_ATTR_MAX_QUEUE_LENGTH attribute mentioned in Queuing applies to the suspended handler queue as well as to the queue for the queuing mechanism. However, because these queues are separate, if one of the queues reaches the predefined limit for storing event occurrences, it does not directly affect the other mechanism.