Cyclic—The frame transmits at a cyclic (periodic) rate, regardless of whether the application has updated its payload data. The advantage of cyclic behavior is that the application does not need to worry about when to transmit, and data changes arrive at other ECUs within a well-defined deadline.

Event—The frame transmits when a specific event occurs. This event is often simply that the application updated the payload data, but other events are possible. The advantage is that the frame transmits on the network only as needed.

Within , a Cyclic frame begins transmit as soon as the session starts, regardless of whether you called the appropriate Write function. The call to the appropriate Write function is the event that drives an Event frame transmit.