NI-DAQmx uses a task state model to improve ease of use and speed up driver performance.
The task state model consists of five states—Unverified, Verified, Reserved, Committed, and Running. You call the Start Task function/VI, Stop Task function/VI, and Control Task function/VI to transition the task from one state to another. The task state model is very flexible. You can choose to interact with as little or as much of the task state model as your application requires.
If you explicitly invoke a state transition that has already occurred, it is not repeated and an error is not returned. For example, if the task has already reserved its resources and, therefore, is in the Reserved state, calling the Control Task function/VI with the Action parameter set to Reserve does not reserve the resources again.