What Is a Queue in LabVIEW?

Issue Details

• What is a queue and how do I use it?
• How can I pass data from one loop into another loop running in parallel?

Solution

A queue is a buffered list that maintains a first in/first out (FIFO) order of data items. A queue in LabVIEW can be used when communicating between processes within a program. You can create a queue using Queue Operations VIs n LabVIEW.

A common example of using a queue is in producer/consumer situations, where one portion of code is creating (or producing) data to be processed (or consumed) by another portion. The advantage of using a queue is that the producer and consumer will run as parallel processes and their rates do not have to be identical. The following image shows the available VIs on the Queue palette, which can be accessed by opening the Functions palette and selecting Programming >> Synchronization >> Queue Operations.

Additional Information

Unlike an array, it is not possible to randomly access elements in a queue. It is strictly a buffer that provides you the ability to enqueue (add/insert) and dequeue (subtract/remove) elements. The only way to view all the elements in a queue is to dequeue them one by one. You cannot perform data manipulation to all the elements in a queue.

Look for example programs in the LabVIEW shipping examples. Open the LabVIEW Example Finder by selecting Help >> Find Examples and then search for Queue in the search tab.

For information on other types of data transfer, see Data Communication Methods in LabVIEW - LabVIEW Help .