General
The master task is active by default.
The fast and auxiliary tasks are active by default if they have been programmed.
Event processing is activated when the associated event occurs.
Operation
The table below describes the execution of priority tasks (this operation is also illustrated in the diagram below).
Phase |
Description |
|---|---|
1 |
Occurrence of an event or start of the fast task cycle. |
2 |
Execution of lower priority tasks in progress stopped, |
3 |
Execution of the priority task. |
4 |
The interrupted task takes over again when processing of the priority task is complete. |
Description of the Task Sequence
The following diagram illustrates the task sequence of multitasking processing with a cyclic master task, a fast task with a 20ms period and event processing.
Legend:
I: acquisition of inputs
P: program processing
O: updating of outputs
Task Control
The execution of fast and event processing tasks can be controlled by the program using the following system bits:
%S30 is used to control whether or not the MAST master task is active
%S31 is used to control whether or not the FAST task is active..
%S32 to %S35 are used to control whether or not the auxiliary tasks AUX0 to AUX3 are active.
%S38 is used to control whether EVTi event processing is active.