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Read and write variable in and out of loop

I have a rather gigantic piece of LV code that controls a series of valve manifolds, mass flow controllers and a few other things.  I have posted a little snapshot of a critical piece of this code that is giving me lots of problems.  It has to do with passing time throughout the sequence.  There is a while loop sitting outside of the sequence that controls the valves and Mass flow controllers that reads the time and creates a local variable called "current time:".  This variable is shown in the figure.  I can see when I run the code that this variable is updated in real time but I would like to pass it throughout the code so valves know when to open and close.  The terminal leaving the variable reads "not executed" when I probe it, so the code thinks that the time is stuck at the moment that I start running the code instead of being updated as the variable is.  I tried switching the variable to "write" but this produces a source-sink violation when I try and pass it on.


I have followed the posts on passing variables between loops but am still stumped as to the problem here.  Any help on this matter would be greatly appreciated!


Thanks very much.

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Message 1 of 6

Looking ar the scrollbars, we can only see about 1% of the diagram in your picture. We cannot troubleshoot like that!


In the code where you read "current time" via a local variable, it is clear that this only happens once per execution of the visible code fragment. Is this all inside a gigantic loop? Assuming we have a big loop: in order to re-execute the visible code all inner loops need to complete. Do they ever?


I don't understand the diagram comment about "changing it to write". Why would even consider this? If you turn a read local into a write local it turns from data source into a data sink, and since the wire would no longer have a data source, the code will be broken.



There are many very suspicious and very dangerous code constructs, such as multiple "event structures..inside while loops..inside case structures". That's really, really bad!

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Message 2 of 6

Thanks for the reply.  Yes, indeed I knew I was in for a chastising and probably should have shot for somethign a bit more manageable for a first go at LabView.  That said,  in an earlier iteration the current time: variable updated and propagated the time throughout the code but sometime in the last few days a change was made that severed that.   The issue is a I need a way to feed the time variable generated in the while loop in the upper right corner throughout.  Any suggestions would be greatly appreciated, code is now attached. 



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Message 3 of 6

Run the program in Highlight Execution (+ keep values) and you can hopefully see how/where it stops.

*screams!*  *shivers*

I just looked at it and it's basically impossible to find any error due to the pure size. You need to create some sub-vi's, much of the stuff you do is similar/identical so it should be easy. You'd also gain alot be clustering controls or putting them in arrays. E.g. your leftmost loop with the events could be 1 array of controls handled be the same event.

About your particular problem i can swear that it only updates once during your whole program due to the inner loops.



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Message 4 of 6

There is no way this can be fixed without starting with a blank slate. Trying to fix that code is like trying to rebuild Pompeii as a luxury resort.


The primary problem most likely started when you placed a few event loops inside the main loop.


Still, I don't consider this VI salvageable, there way way too many design rules broken. Even the front panel is a complete mess. Looks like you blindly copied code sections on the diagram. Why are there so many stop buttons???

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Message 5 of 6

Point taken!  Thanks for taking a look.


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