Stop syncronization of 2 while loops

Hello all!
Now in my project I got a serious problem. I have 2 while loops. One (loop 1) keeps receiving UDP messages
from an external device and send a cetain type of message to another while loop (loop 2). The cycling time of 1st loop is
300ms (it receives a UDP message every 300ms), the cycling time of the 2nd is 30s (30s is the receiving period of the certain type
UDP message sent by loop1, and I used a notifier to transmit this message to loop 2, so the cycling time of second loop is 30s).
At last when the num of the certain type of UDP messages received reaches 4, I want both loops stop, so as the program. However,
at last both loops stopped but the program no!
I'm quite sure it's the problem of the 'stop' of 2 loops, cuz when I don't use the notifier, not to control the cycles of the loop 2,
at last both of the loops stop and the program could stop. But with the control of cycles of loop 2 (I mean the loop passes on cycle
when receiving the certain type of message from loop 1), the whole program doesn't stop when both loops stop.
So in this case, 2 loops with data dependency run with different cycling time, is it possible to syncronize the stop, in order to
stop the whole program when both loops stop. Thanks in advance!
Chao

Hello Mister!
I'm not sure in which way I could show you better my code, since the main vi contains tens of subvi.
This pic doesn't show everything. I should explain that the higher loop is loop one which is receiving UDP
message and send a certain type of UDP message to the lower loop.
If you have a better idea about showing my code better, please tell me. Thank you
Attachments:
Immaginelabview.JPG ‏225 KB

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First, please use a smaller font when composing your messages.
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I am working on a program for homework that states E5.4) Using a single Whil eLoop, construct a VI that executes a loop N times or until the user presses a stop button. Be sure to include the Time Delay Exress Vi so the user has time to press the stop botton.
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Rajster16 wrote:
Using a single Whil eLoop, construct a VI that executes a loop N times or until the user presses a stop button.
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Attachments:
tab control.vi ‏24 KB

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tab control fix maybe.vi ‏26 KB

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Attachments:
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Dataflow!
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Hi RawtoLV,
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Hi,
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help_pauseWhileLoop1.png ‏56 KB
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Event Structures and Do /While Loops

I have an Event Structure inside a Do/While Loop. One of the buttons in the event is STOP which stops the do while. The Stop Button itself is inside the event as suggested in the help. My problem is when I hit the stop button everything inside the Do/While runs 1 more time. Other than than the code works perfectly. is this normal behavior for a Do/While ..Event Structure??

The attached file is the code in a nutshell. I know it can sometimes be diffcult to TS w/o the actual code. Prob is I wrote it in LV2011 on the Lab PC and I have LV2010 at my desk. I don't have internet access in the Lab..of course.
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To count the number of while loops, do you just have to attach a DBL indicator to the little i box in the while loop of the program?

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Hi Ssteel,
Just some additional observations/tips on your code...
1. I notice that you have a standard stop button going into a "run if true" stop condition of the while loop. In this cercumstance it is common to have the stop condition set as "stop if true". You can change this by right clicking the stop terminal and enabling the "stop if true" property. Obviously, it somewhat depends on your design preferences.
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Rich R
Applications Engineer
National Instruments UK & Ireland

The demand of my application is that i can not replace for loop with a while loop.because i need fixed number of iterations and as far as i know fixed iterations could be only with possible with the for loop.

the demand of my application is that i can not replace for loop with a while loop.because i need fixed number of iterations and as far as i know fixed iterations could be only with possible with the for loop.
your recommended second option that i could add true/false case.
this true/false case must be inside the for loop or outside the for loop?if this case is inside the for
loop, how can i send stop command from outer while
loop?
more over do you have any example for this please?
thanks"

You can execute a fixed number of iterations using a while loop by comparing the iteration count to the number of iterations you want and wiring the output of that comparison (e.g. Less Than or Equal To) to the continue (or stop) terminal of your while loop. Which comparison you use depends on personal preference, where you wire the desired count and the interation count, and whether you're using the while loop as Continue if True or Stop if True.
Ben gave you step-by-step instructions in response to your previous question. Look here for Ben's response.
Ben's response looks pretty good and detailed to me. It certa
inly deserved better than a 1-star rating.

One stop button to control multiple loops?

I want to use on stop button to stop mutilple while loop at the same time. But if I put the stop button outside the while loop, it is functional.
Is there any way to do that?
Thanks

cguan wrote:
But if I put the stop button outside the while loop, it is functional.
I don't think "functional" is the right word here.
I often use event structures, e.g. as in my example posted here. This allows you to keep latched mechanical action for the stop button.
For a queued state machine, you would use the error to stop the loop that waits for the queue. Here is an example for that.
The most appropriate method really depends on the situation. Can you post some code?
LabVIEW Champion . Do more with less code and in less time .

How to stop execution in while loop without stopping execution of other loops in the same vi

HI
I am quite a novice in Labview.
I have a problem in my project. I used a while loop inside my vi to build an array of ten values along with other loops. Then I used a stop button to stop manually the while loop. But it seems like the loop doesn't stop in the middle of the array building and so other loops in the vi doesn't work until the while loop finishes building the array and as soon as while loop execution is over, the complete vi stops. But all that I wanted was to build the array using the shift register along with the control to stop building array anytime. And not to stop execution of other structures when the while loop finishes.
Can anyone help me?
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Hi Rahul,
Modified ur Vi to work with single button.
But the subtract case is not in any loop.
So, once both the loops stop, the subtract case will execute only once. Depending on state of subtaract boolean at that time, corresponding case will be executed and the Vi will stop.
so think of a logic where u can put this also in a new loop.
Or you can also incorporate it in one of the two loops and pass the other loop's data to it.
Let us know how you will proceed in this regard
I am posting your VI as well a VI with my modifications VI in Labview 7.0 so that Thomas can give his suggestions too
Plus, always keep a time delay in your while loops.
Oh sorry, the "arrayinouttestnewfinal.vi" is the modified vi
Regards
Dev
Message Edited by devchander on 01-10-2006 06:15 AM
Message Edited by devchander on 01-10-2006 06:19 AM
Attachments:
arrayinouttestnewfinalnew4.vi ‏59 KB
arrayinouttestnewfinal.vi ‏63 KB

How do I create a start/stop button for each separate while loop within my program, when each of them does a different task?

I have a multimeter VI with separate while loops to accomplish the different tasks of reading voltage, current, etc. Each while loop has a stop button, but I need a button that will have to be pressed in order for the while loop to even start. I tried putting another while loop around the present one, but it still has to run once before it will stop. I want the user to have to press the button before it runs, because they interfere with each other.
I am just learning so patience and your kind assistance is greatly appreciated!
ElectroKate

iZACHdx wrote:
Hello,
I'm not entirely clear with everything you have going on and what you want your final functionality to be, but you can use sequence structures to prevent a loop from starting until the user presses a button like this:
-Zach
I have to ask, why is an NI employee using examples using sequence frames? The same thing could be accomplished using data flow by simply wiring the value of the first stop button out of teh first while loop and connecting it to the second loop. This would then use data flow to control the sequence. Why show new users bad programming methods?
As to the original question I would concur with altenbach on using an event structure.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

Stop syncronization of 2 while loops

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