First, some basic suggestions:
- Make an Array of Boolean Controls on the Front Panel. Drag the array "sideways" until you have 8 Controls showing (they'll all be greyed out, since the Array, at this point, is empty). Click to turn on the right-most one, which will bring into existence all of the Controls. Now turn it off. You now have an 8-element Array of Boolean that you can immediately wire into Boolean Array to Number. It also "looks prettier" on the Front Panel.
- Do the same for the 8-element Boolean Indicator Array. Note that once you have the Arrays on the Front Panel and have them sized properly, you can get rid of the Array Index (since you can "see" all the elements) by right-clicking the Array on the Front Panel, choosing Visible Items, and turning off Index Display (I think that's what it is called).
- See how dramatically this "shrinks" your While loops!!
This is the second time today I've basically advised someone to "Write the Documentation First". It is not at all clear what you want to do, but it is pretty clear that you are not "doing it correctly". Try writing down a description that says something like the following:
- I want to simultaneously collect signals from X, Y, Z, A, B, and C.
- I want to sample each one at the same time.
- I want to sample at 100 Hz.
- As each point comes in, I want to process it as follows: (description here)
- When (condition description here) occurs, I want to (further description here).
Now, it may well be that you are mostly doing "simultaneous monitoring", hence don't need "immediate processing". In which case, you might say
- For Channels X, Y, and Z, I want to sample at 1KHz, and deliver 1000 points once/second for further processing.
- For Channels A, B, and C, I want to sample at 1Hz, and deliver each point for further processing.
- I want to display (whatever) and save (whatever) to a log file.
- I will use Buttons <Start> and <Stop> to control acquisition.
One of LabVIEW's strengths is that it is a Data Flow language, which means that it is inherently parallel and can have multiple loops running more-or-less simultaneously and asynchronously. Something that is very useful for data acquisition/control situation is the Producer/Consumer Design Pattern -- you have a Producer loop running and gathering data (say, 1000 points at 1KHz), and as fast as the data comes it, the Producer puts it into a Queue which immediately goes to the (parallel) Consumer Loop, patiently "waiting" for data. When the data arrives, the Consumer "eats it up", displaying it, writing it to disk, doing FFTs, whatever. Because the Producer loop is mainly "waiting on the hardware", it tends to use a tiny fraction of the CPU time, leaving the bulk of the time to the Consumer.
If you don't know about this, there is Sample code available. Open LabVIEW, go to File, New ... (the dots are important), and look under Templates for Producer/Consumer Design Pattern (Data). Choose it, let it build, then study it. Now adapt it to your situation.
Bob Schor
