The Frame Scheduler time base is fundamental because it determines the duration of a minor frame, and hence the frame rate of the program. This section explains the different time bases available.
When you use multiple, synchronized Frame Schedulers, the master Frame Scheduler creates an interrupt group, a hardware mechanism that distributes the time-base interrupt to each synchronized CPU. This ensures that minor-frame boundaries are synchronized across all the Frame Schedulers. (For details of the interrupt group mechanism, you can read "Group Interrupts on Challenge and Onyx Systems," a technical paper distributed with the REACT/Pro product.)