Jitter in the top-priority user program, what is the cause?
Question:
Why can there be jitter in the top-priority interrupt in the user program?
Answer:
Apart from the 8 interrupt tasks that can be specified by the user there are another 6 system interrupt tasks (e.g. CAN synchronisation, ground fault monitoring, 250 µs motor control, ...). These are all processed with a higher level of priority than the user tasks.
The higher-priority system tasks cannot be interrupted by the user tasks. The starting time of the user tasks fluctuates accordingly (jitter).