5 Understanding Programming
5-12
CJ2 CPU Unit Software User’s Manual
There are basically two types of tasks.
*1 Cyclic execution (i.e., execution once per cycle) can be performed for an interrupt task just as with cyclic tasks
by using Task Control Instructions to turn ON the interrupt task. (These tasks are called extra cyclic tasks.)
*2 Do not use SFC programs in interrupt tasks. They will not execute normally. SFC programs can be used, how-
ever, if the interrupt tasks are executed as extra cyclic tasks.
Type of task Description
Applicable pro-
gramming lan-
guage
Execution conditions
Cyclic tasks Executed once per
cycle
Ladder diagrams
SFC
ST
Executed when one of the following methods is
used to place the task into READY status.
• Setting the Activated at the start of operation
property using the CX-Programmer (program
property setting)
• Turning ON the task by using a Task Control
Instruction
Interrupt
tasks
*1,*2
Executed when a
specific condition
occurs. The pro-
cess being exe-
cuted is
interrupted.
Ladder diagrams
ST
An interrupt task is placed into READY status when
the interrupt conditions that is set for it occurs. Con-
ditions can be set for each of the following interrupt
tasks.
• Power OFF interrupt tasks
• Scheduled interrupt tasks
• I/O interrupt tasks
• External interrupt tasks
• Input interrupt tasks (CJ2M CPU Units only)
END
END
END
Cyclic
task 1
Cyclic
task n
I/O refreshing
Assigned
to a task.
Program A
Program B
Program C
Programs assigned to tasks are
allocated in order.
Interrupt
condition
When specified conditions are
met, execution of the other tasks
is interrupted and the program in
the interrupt task is executed
Interrupt
task
Assigned
to a task.
Assigned
to a task.
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