Discrepancy between execution time of state machine and flat code

I am trying to optimize the performance of my application, and I've found that the same code executed as a case in a state machine, and flat on the block diagram takes a dramatically different amount of time to run. I'm trying to figure out what I'm missing here. The picture shows a test vi I threw together (the next post will have the diagram image for the "Add New" case of my Buffer Engine.vi - basically the same as what is in frame 5). The fifth frame in the sequence is what I am concerned about. It shows that executing the case in the state machine takes ~700ms, and flat, ~113ms.
Any thoughts?
Chris
Attachments:
Test Times.jpg ‏124 KB

Thanks for the suggestion Altenbach. I had to insert a for loop to replace array subset indivually for each column of new data to place in the buffer, but even with the extra processing, the result was about 80% faster. I guess I'll have to come up with a system to track where to place the data (it was convenient to always drop the data at the end..), but that shouldn't be an issue.
However, this suggestion doesn't address the original concern. The same array resizing was going on in both the subvi and the sequence frame. This improvement should increase the performance of each, but doesn't explain the difference.
As an aside, I contemplated using a queue, but without the ability to dequeue from both the beginning and the end, I don't see how I can use them for this. I want to trash the oldest data, not hold up the acquisition. In any case, I don't think it would be faster because the memory isn't pre-allocated. Now I am considering just storing the data in a control, and passing the reference as necessary. The question is, is reading the value from a control faster than reading from a shift register?
Thanks again.
Chris

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Test Setup X01.vi ‏16 KB

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This account is no longer active. Contact ShadesOfGray for current posts and information.
Attachments:
serialUtil_V3_DFG.zip ‏137 KB

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metzler CLAD
Solved!
Go to Solution.

I'm not sure exactly what you are asking, but it sounds like you want to script a bunch of tests and if the user says stop, to immediately stop the current test and abandon the others? I'm going to assume that you know how to clear the array so that it will abandon the others, so I'm guessing that you are having trouble abandoning the current test? If this is indeed the case, then the problem is that you are not able to propagate the message from the main VI FP which is the GUI to the sub vi which is the test, where the test may or may not have a GUI (FP visible) of it's own. Threading was the first thing to come to mind, but this may not be necessary using events.
You can do this by passing a refnum of the stop button to the subVI, where you can then add that wait to the event case structure.
I've attached 2 VIs, mainvi.vi which is just a loop displays the count*2 (number of seconds passed since running) that will call subvi.vi and then check to see if the stop button is pressed. mainvi.vi is by no means a state engine, it is just a simple loop for demonstration purposes. subvi.vi just waits 2 seconds and leaves, it is a better structured state engine with an init state to start a poll case to wait for events and an exit state to clean up. You can modify this any way you wish to get it to do what you want. You will note that even if subvi.vi is being executed, it will terminate immediately when the stop button is pressed.
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A
Attachments:
mainvi.vi ‏17 KB
subvi.vi ‏33 KB

Discrepancy between execution time of state machine and flat code

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