Publishing Interval
The PublishingInterval is configured as part of a Publisher configuration. It specifies the time intervall in which frames should be published and correlates with the BaseTime that has been configured in the TwinCAT Real-Time settings.
Example: the following screenshot shows a system which has a BaseTime of 1ms configured in its TwinCAT Real-Time settings.

When configuring a Publisher, the PublishingInterval now correlates to this BaseTime. The following screenshot shows a configured PublishingInterval of 100ms (100 ticks * 1ms BaseTime).
