Specifications

34
1768-SG001A-EN-P -- March 2006
CompactLogix Selection Guide
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A Logix controller uses three types of tasks. Use the following table to choose the
appropriate type of task for each section of your logic.
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All of the time
Continuous task
The continuous task runs in the background. Any CPU time not
allocated to other operations (such as motion, communications, and
other tasks) is used to execute the programs in the continuous task.
• The continuous task runs all the time. When the continuous task
completes a full scan, it restarts immediately.
• A project does not require a continuous task. If used, there can be
only one continuous task.
• At a constant period (e.g.,
every 100 ms)
• Multiple times within the scan
of your other logic
Periodic task
A periodic task performs a function at a specific period.
• Whenever the time for the periodic task expires, the task interrupts
any lower priority tasks, executes one time, and then returns control to
where the previous task left off.
• You can configure the time period from 0.1 ms to 2000 ms. The
default is 10 ms. It is also controller and configuration dependent.
• The performance of a periodic task depends on the type of Logix
controller and on the logic in the task.
Immediately when an event
occurs
Event task
An event task performs a function only when a specific event (trigger
occurs. In a 1768 CompactLogix controller, the trigger for the event
task can be:
• certain motion operations.
• consumed tag.
• EVENT instruction.
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PPhhaasseess
The PhaseManager option of RSLogix 5000 software gives you a state model for your
equipment. It includes the following components:
y Phase to run the state model
y Equipment phase instructions for programming the phase
y PHASE data type to link the phase to other equipment and higher-level systems
PhaseManager uses the following states:
To develop PhaseManager programs, you need:
y Logix5000 controller with firmware revision 15.0 or later
y Communication path to the controller
y RSLogix 5000 software version 15.0 or later