The XCx Multi-Tasking System
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Operating Manual XCx 300 / 500 / 540 Version 09/08
8.2
User Tasks
User tasks are all tasks that can be inserted by the application
programmer.
The default task is also on the user task level. It is the user task with
the lowest priority. The default task is executed when no other user
task is active.
Incorrectly or inappropriately selected user task
settings for type, priority, interrupt mode, etc.
–
especially in conjunction with longer program
runtimes
– can lead to controller malfunction when
essential operating system tasks are displaced.
See section Task Priorities.
You can use various types of user task.
8.2.1
Cyclical tasks
Cyclical tasks execute the programs assigned to them within a defined
interval under a user-defined priority.
In MULTIPROG you can give the individual tasks a priority between 0
and 31. Task 0 has the highest priority, task 31 the lowest. The task
with the highest priority is called first. The user-task priorities are
mapped to the priority levels of the real-time operating system. (See
section Task Priorities)
If the watchdog time of a cyclical task is higher than the set interval
time and task execution has not been completed, one or more
execution cycles will be omitted.
