Omron NJ-series User Manual page 146

 Execution Timing When the Execution Condition Is a Condition Expression
for a Variable
The condition expression is evaluated for a match inside the primary periodic task. This means that
the event task will be executed immediately after the first execution of the primary periodic task after
the specified value of the variable meets the condition expression. However, if there are tasks with a
higher execution priority than the event task, those tasks will be executed first.
Example 1: Project with a Priority-16 Periodic Task and an Event Task Execution with a Priority of 8
The event task is executed immediately after the first execution of the primary periodic task
after the condition expression is met. The execution priority of the event task (execution priority
of 8) is higher than the execution priority of the priority-16 periodic task. The priority-16 periodic
task is therefore executed after the event task is executed.
Execution
priority
High
Primary periodic
task
Event task (execution
priority of 8)
Priority-16
periodic task
Low
Example 2: Project with a Priority-16 Periodic Task and an Event Task Execution with a Priority of 48
The execution priority of the event task is lower than the execution priority of the priority-16
periodic task. The event task is therefore executed after the priority-16 periodic task is
executed.
Execution
priority
High
Primary periodic
task
Priority-16
periodic task
Event task (execution
priority of 48)
Low
NJ-series CPU Unit Software User's Manual (W501)
Primary period
IO UPG MC IO UPG MC
Value is assigned
to variable in user
program.
Task period
Interrupted.
Primary period
IO UPG MC IO UPG MC
Value is assigned
to variable in user
program.
Task period
Interrupted.
IO UPG MC IO UPG MC
Event task is executed
Condition
immediately after the
expression
condition expression is met.
is met.
IO UPG MC IO UPG MC
Condition expression
is met.
Event task is executed
immediately after completion
of the periodic task.
5 Designing Tasks
IO UPG MC
Interrupted.
IO UPG MC
Interrupted.
5-19
5