These two statements from the Logix5000 Controllers Design Considerations manual seem to contradict each other. Does anyone have some clarification?
If I run logic within a periodic task with a priority higher than the I/O processing task than my understanding is that the I/O processing task will not interrupt the periodic task and I/O tags will not change state during the periodic task execution.
In Logix5000 controllers, I/O values update at a period, requested packet
interval (RPI), that you configure via Module Property dialog in the I/O
configuration folder of the project. The values update asynchronously to the
execution of logic.
The module sends input values to the controller at the specified RPI. Because this
transfer is asynchronous to the execution of logic, an I/O value in the controller
can change in the middle of a scan.
Higher-priority tasks take precedence over the I/O task and can impact processing.
If I run logic within a periodic task with a priority higher than the I/O processing task than my understanding is that the I/O processing task will not interrupt the periodic task and I/O tags will not change state during the periodic task execution.