Rockwell Automation Publication 5069-UM002A-EN-P - January 2019 183
Develop Control Applications Chapter 8
Table 11 explains the types of tasks you can configure.
The CompactLogixâ„¢ 5480 controller supports up to 32 tasks. Only one of the
tasks can be continuous.
A task can have up to 1000 programs, each with its own executable routines
and program-scoped tags. Once a task is triggered (activated), the programs
that are assigned to the task execute in the order in which they are grouped.
Programs can appear only once in the Controller Organizer and multiple tasks
cannot share them.
Table 11 - Task Types and Execution Frequency
Task Type Task Execution Description
Continuous Constant The continuous task runs in the background. Any CPU time that is not allocated to other operations (such as motion and
other tasks) is used to execute the programs in the continuous task.
• The continuous task runs constantly. When the continuous task completes a full scan, it restarts immediately.
• A project does not require a continuous task. If used, you use only one continuous task.
Periodic At a set interval, such as every
100 ms
A periodic task performs a function at an interval.
• Whenever the time for the periodic task expires, the task interrupts any lower priority tasks, executes once, and returns
control to where the previous task left off.
• You can configure the time period from 0.1…2,000,000.00 ms. The default is 10 ms. It is also controller and
configuration dependent.
Event Immediately when an event occurs An event task performs a function when an event (trigger) occurs. The trigger for the event task can be the following:
• Module input data change of state
• A consumed tag trigger
• An EVENT instruction
• An axis trigger
• A motion event trigger
You can configure an optional timeout interval for missed event triggers. The timeout interval causes the event tasks to
execute even in the absence of the trigger. Set the Check the Execute Task If No Event Occurs Within <timeout period>
checkbox for task.
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