LabVIEW
Labview program stop after a few while loop
Your loop will not stop until you press the stop button, but you'll get an automatic error handling modal popup*. What does the error say?
*because you don't have the error out connected at the file IO. You won't get that popup if you wire the error out to the loop boundary, for example. Still you should handle or display the error for troubleshooting anyway.,
@keysuccess: Although you've been a member of the LabVIEW Forums longer than I, I'm guessing it has been a number of years (a decade?) since you did any serious LabVIEW programming. I've taken the liberty of slightly rearranging your VI, turning off the icon displays on Controls and Indicators, straightening wires, turning on the labels of the two DAQ functions that show up as question boxes, moving some controls outside the While Loop, and using the Error Line to also stop the Loop if an Error occurred. I also added a Shift register so the first time you run, you start a new file (if you really want to start by appending to an existing file, feel free to remove my "improvement" and an Error Indicator so you could "see" the Error Message. Here's a Snippet with my changes:
Incidentally, it looks like the two ? functions are from Agilent 2000-3000 X-Series Instruments (whatever those are).
So what happens inside the loop? You do a Read Waveform, which brings in some data (no idea how much, no idea how it is timed, nor how much time it takes). Once this function finishes, the data are sent to a Waveform Graph (I'll assume this takes 0.1 sec) and written to a Export Waveform to SpreadSheet File function, opening a new file the first time through and appending to the file for all subsequent loops. The time for this function depends on the amount of data written, and will probably increase on subsequent loops (because the file is always opened and closed with each call, meaning subsequent calls have to "find the end" and append, but that should be fairly rapid). I'll assume this process takes less than a second.
You also have a 10 second Wait (ms) in the loop. Since LabVIEW's Principle of Data Flow means that the loop can't "move on" to its second time through until the Wait is satisfied. So (at least) 10 seconds after the first Read Waveform, you'll do the second, and (at least) 10 seconds later, the third. Could this "enforced" slowdown in reading the data from your Agilent (I'm assuming, here) device cause some kind of "backup" that results in an Error on the Error Line? Using an Error on the Error Line as an additional way to stop the Loop can help you diagnose the problem when it first occurs.
Try running this version, and report back on the Error. Also, find out what happens if you ask for data (however you've coded your instrument to provide it) but only do one Read Waveform every 10 seconds -- does it, in fact, get backed up and fail?
Bob Schor
@keysuccess wrote:
Attached is the complete program.
That's just partially redacted picture of a block diagram. A picture is not a "complete program".
- You are never using the boolean in the shift register, so why is it even there?
- I strongly recommend to do all path operations using strip path/build path. It is much more fragile doing everything as strings followed by "string to path".
- While you can change the lower two source channels during run, you cannot change the topmost, because the terminal is outside the loop. Is this as designed?
- Communicating with an instrument cannot happen in parallel, so you should probably serialize the IO. Currently there is no way telling what happens in what order. You could even combine all into a FOR loop.
- Even if you keep it separate, at least make the parts look the same instead that random wire mess with three completely different layouts for the same functionality.
- Is the loop rate slow enough to guarantee that all file IO can complete in the desired loop time?
- I would use more digits for the iteration number. This way the numeric and alphabetic sorting of the file names remains identical. (file0001.txt vs. file1.txt)
- Why do you ignore the error in the lower two code trains?
- Why do you even extract the [Y]? Just graph the waveform! This way x0,dx are correct.
- I recommend to keep the polymorphic selector next to the function and not give it easter-egg colors.
- etc. ...
