I take it you are just learning LabVIEW on your own (as you don't seem to know about For loops, arrays, Event Structures, parallel loops, and data flow). There are some excellent tutorials that will quickly get you started on the basics -- look at the end of this post.
Some basic suggestions include:
- Use a For loop, where you compute N outside the loop from Start, End, and Step voltages.
- Bring Start, End, and Step voltages into the loop on wires, avoiding the use of Local Variables (try to avoid Local Variables).
- Same thing with File Path (if you don't plan to fill it, simply eliminate it -- you will get the default Dialog if Empty behavior).
- You don't need a Frame sequence. You almost never need a Frame in LabVIEW, and should even more rarely use a Frame Sequence.
- Graphs are, by design, "static". If you want a graph when the loop exits, simply bring your X and Y single-iteration values out the right side of the For loop where they will be turned into arrays. You can then wire these arrays directly into the Graph. (You may want to look at how to do this -- I can never remember whether you wire the X array and the Y array, or whether you combine X and Y pairs and wire an array of pairs, but the LabVIEW Help (from the Help menu, or Control-H) will "help" you).
- Inside the For loop, you can set the timing by simply putting a Wait function (not an Express VI!) from the Timing Palette inside the loop anywhere and wiring 2000 (milliseconds = 2 seconds) to its input. Data flow says that the loop will be constrained to run at that speed.
- Thinking more about what you probably want, consider using a Chart (inside the loop) rather than a Graph (which belongs outside the loop) to see the data as it evolves.
- When you exit the loop and have all of the X and Y values nicely in arrays, computing the average should be a piece of cake.
Good luck with learning LabVIEW. Follow the tutorials, do examples, and don't hesitate to ask for constructive criticism (which is what this is intended to be).
Bob Schor
