The PublishingInterval, the SamplingOffset the PublishingOffset and the timestamp in the NetworkMessage header shall use the same time base.
If an underlying network provides a synchronized global clock, this clock shall be used as the time base for the Publisher and Subscriber.
The beginning of a PublishingInterval shall be a multiple of the PublishingInterval relative to the start of the time base. The reference start time of the PublishingInterval can be calculated by using the following formula:
Start of periodic execution =
current time + PublishingInterval – (current time MODULO PublishingInterval)
Current time is the number of nanoseconds since the start of epoch used by the reference clock.
PublishingInterval is the duration in nanoseconds.
Start of periodic execution is the number of nanoseconds since the start of epoch which is the next possible start of a PublishingInterval.
Figure 28 shows an example how to select the possible start of a PublishingInterval.
Figure 28 – Start of the periodic publisher execution
The different timing offsets inside a PublishingInterval cycle on Publisher and Subscriber side are shown in Figure 29. The SamplingOffset and PublishingOffset are defined as parameters of the UADP WriterGroup. The ReceiveOffset and the ProcessingOffset are defined as parameters of the UADP DataSetReader in 6.3.1.4.
