# General description and overview

Named semaphores are set up to synchronise the NC with one or more external thread(s). In each cycle, these semaphores are issued once, as a result of which the external threads waiting for them are woken up and they can do their work. External threads are integrated into overall scheduling depending on their priority.

Synchronisation with an external thread

As threads cannot be stopped across processes, external threads must behave cooperatively. Depending on the external thread's priority, its runtime is to the detriment of the asynchronous NC thread or to the detriment of the guaranteed Windows time.