Chapter 7 Introduction of Axis Parameters
7-5
① The execution conditions for the cyclic task and freewheeling task are met at the same time. The
cyclic task is executed first because of its higher priority.
② When the cyclic task execution is finished, the freewheeling task execution starts.
③ The controller will execute the system processing if there is no other task after the execution of
the freewheeling task is completed.
④ The execution of the freewheeling task continues since the high-priority cyclic task request has
not arrived.
⑤ The cyclic task interrupts the freewheeling task execution and the controller executes the cyclic
task because of the arrival of the high-priority cyclic task request during the execution of the
freewheeling task.
⑥ The controller continues to execute the part of the low-priority freewheeling task, which has not
been executed yet when the execution of the cyclic task is completed.
⑦ When the execution of the freewheeling task is completed, the controller executes the system
processing due to no other task request.
⑧ When the system processing is completed, the execution of the freewheeling task continues due
to no high-priority cyclic task request.
When three tasks are executed in mixture (Event task, Cyclic task and Freewheeling task)
IO
User
program
User
program
Task execution
co ndition met
Execution
finished
User
progr am
Pause
Pause
The event task has not been triggered
Task execution time
Task execution
finished
IO
User
prog ram
Time interval between tasks
Time inter val between tasks
IO
User
prog ram
Syst em
processing
IO
User
program
Task execution ti me
Execution
finish ed
Task execution
condition met
Pause
Execution
finishe d
Execution
cond itio n met
Execution finished
Tas k execution time
Task ex ecution time
IO
User
program
Execution
finishe d
Task execution
condition met
2
3
4
5
6
8 9
10
7
Syst em
processing
Task execution
condition met
System
processing
Event Task
( )Priority 1
System
processing
Priority
High
Low
IO
Freewheeling task
( )Priority 2
Cyclic task
(Priority 3)
Task execution
conditio n met
IO
User
pro gram
Task execution
co ndition me t
Task execution time
Time inter val between task s
1
11
12
① When the conditions for execution of the freewheeling task and cyclic task are both met, the
freewheeling task is executed first because the priority of the freewheeling task is higher.
② The cyclic task execution starts when the freewheeling task execution is completed.
③ When the cyclic task execution is completed, the controller executes the system processing due
to no other task request.
④ The freewheeling task is executed when the system processing is completed.
⑤ When the freewheeling task execution is completed, the controller executes the system
processing due to no other task request.
⑥ The freewheeling task is executed when the system processing is completed.
⑦ The freewheeling task execution continues because the freewheeling task has a higher priority
than the cyclic task although the execution condition for the cyclic task is met. And the cyclic
task waits to execute.
⑧ The event task interrupts the freewheeling task execution because the event task has the
highest priority and the execution condition for the event task is met.
⑨ The controller continues to execute the part of the low-priority freewheeling task, which has not
been executed yet when the event task execution is completed.
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