A frequent comment I have when I look at someone else's LabVIEW code (such as yours) is "What are you trying to do?". Your code gives very little in the way of clues. The VI has no documentation of any kind -- there is no VI Description, there are no Free Labels noting the purpose of the loops, variables are named "Cluster" (no clue as contents) or "Data" (duh!), loops are of the "Do Forever" category (so you know this is a non-workable piece of code), there are parallel loops whose purpose is unclear, an Event Structure that appears to be superfluous, etc.
Here's a serious suggestion: Open your favorite Word Processor and write a page or two description of What you want to accomplish. Give absolutely no thought to How to accomplish it -- don't think about LabVIEW, think about the Task To Be Done.
One place to start is with the Data. What is the nature of the data? From where is it coming? What do you need to do about it? Are you simply logging it (to where?), do you need to process it and make decisions as it come in (what decisions? do certain data change the flow of the program?), are there "Start" or "Stop" controls that you want to use to control the process? What kind of interaction does the Operator have with the Program and its associated Data? Do the Data need to be displayed, and if so, what is a useful format for the display?
A very common beginner "Design Pattern" is to place everything on a gigantic Block Diagram that requires multiple large monitors or, alternatively, viewing the Block Diagram through a (relatively) tiny window, making it impossible to see the Big Picture and structure of the Design. One excellent way to "collapse" huge Block Diagrams is to identify sub-Tasks and write them as sub-VIs. You apparently have no sub-VIs in your code.
What is the purpose of so many parallel loops (and "because I can" is not a good answer!)? I can see an initial sub-VI called "Get Logon Credentials" that runs and returns Success or Failure. If Failure, you simply stop the program (by not doing anything else). Again, what is the nature of the Data from VISA? What are you expecting, what do you need to do with it, and what governs when you are done? It is not acceptable to "Abort" or "Kill" a running Program -- there needs to be a Stop condition, and it needs to be incorporated into the Program so that things that are Started (such as Queues and VISA Resources) are properly Stopped. You do have "stopping" code in your Block Diagram, but you can never execute it as the code is currently written.
Find someone with at least a year's experience writing serious LabVIEW Programs (someone with LabVIEW Certification of almost any sort would be preferred). Apprentice yourself to him (or her), and try to Learn from Better Examples.
Bob Schor
