LabVIEW Example—Software-Timed I/O

Note  Although this example is written for LabVIEW users, the principles apply if you are using another ADE, such as LabWindows/CVI.

• A Timed Loop running off the system's time sources (millisecond or microsecond resolution) accomplishes the task. Configure the Timed Loop to run at the desired rate.
• Configure all tasks to be software-timed (on demand).
• The Timed Loop provides feedback to the application as to whether the previous iteration completed in time. It does this through the "Finished Late [i-1]" node.

Sample Block Diagram

Notes

• The Timed Loop allows the application to adjust its period from within the loop, allowing the implementation of dynamic timing algorithms for control.
• Lower-priority processes can execute while the Timed Loop waits until its next iteration.
• Other software timing methods include the use of the Wait and Wait Until next multiple VIs (with microsecond or milliseconds resolution). These methods provide no feedback when the application falls behind.