Create a periodic task

Periodic tasks perform a function at a specific rate. The tasks are initiated after a specified time period. Tasks interrupt lower priority tasks and all programs assigned to the task execute or scan once from top to bottom. After a single scan, the output update triggers and other tasks restart at the point of interruption. A periodic task executes at a fixed interval between 0.1 milliseconds and 2,000,000 milliseconds, in increments of 1 millisecond.
  1. On the explorer bar, select Execution icon
    Execution
    .
  2. Right-click the controller and select
    New task
    .
  3. Configure the settings of the task:
    • Name
      . Enter the name of the task.
    • Description
      . Enter a description of what the task does.
    • Type
      . Select
      Periodic
      . This is the default.
    • Period
      . Enter the frequency to perform the task. Reducing the Period rate increases how often the task performs a function. Increasing the frequency causes other tasks in the controller to perform at a slower rate.
    • Task Priority
      . Enter the priority level of the task. A lower number indicates a higher priority for the task. A task assigned a 1 is a higher priority task than a task assigned a 15.
    • Watchdog
      . Enter the maximum time in milliseconds the task can run before triggering a motor control fault.
      IMPORTANT: For safety tasks, enter a watchdog less than or equal to the
      Period
      rate.
    • (optional)
      Disable automatic output processing to reduce task overhead
      . Position the switch to Toggle On icon
      On
      to help prevent external output modules from updating the data table values of the controller at the end of the task scan. Position the switch to Toggle Off icon
      Off
      to enable updates.
    • (optional)
      Inhibit task
      . Position the switch to Toggle On icon
      On
      to help prevent the controller from performing this task. Position the switch to Toggle Off icon
      Off
      to enable the controller to perform this task.
      TIP:
      FactoryTalk Design Studio
       pre-scans inhibited tasks. If the controller is already in Run mode, the task is enabled and the task is not pre-scanned again.
  4. Select
    Create
    . The task appears in the
    Tasks
     folder.
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