Controlling a SubVI with while loop from another VI

Dear All,
this might be an easy Question but i couldn't catch an answer for it.
first of all i have a VI which i will use as a subVI , this VI is simply as shown in the "test_out of scope.vi" attached file
now i will use it inside another VI called "Main VI" as shown in the file "Main_VI.vi"
i'm just wondering , why couldn't i control the "Frequency" and "Stop" as i can do so while running the SubVI only without accessing it from another VI ?
isn't it possible to access objects inside a while loop from another VI if i just connected them in the connection Pane terminals ??
Thanks in advance to everybody
Message Edited by Mohammed.Ashraf on 06-09-2009 10:27 AM
Eng. Mohammed Ashraf
Certified LabVIEW Associated Developer
InnoVision Systems Founder, RF Test Development Engineer
www.ivsystems-eg.com
Attachments:
Main_VI.vi ‏10 KB
test_out of scope.vi ‏30 KB

Do you need the sub-vi to run iterations for an undertermined period of time?
If so, then why not implement it as a parallel loop to the main one. Maybe part of a consumer loop.
If not. Where the main loop would take care of each iteration and call the sub-vi in one shot. Then no need for a loop in the sub-vi.
It's all a matter of how you want the software to behave. Have you looked at Event Structures?
R

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SubVI with while loop + event structure not working in multi tab VI

Hello Everyone,
I am developing an interface for the control of a prober using Labview 2012, and I am stuck with some issue.
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The VI consists of several tabs: Prober Initialization, Wafer Handling, Wafer Map, Status, Error.
The sub-VI can:
1/ initialize the grid to display the map (sub VI Init Grid not provided here)
2/ import XY coordinates from a txt file (sub VI Wafer Map Import)
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4/ and when a die position is double clicked, and the boolean "Edit Wafer Map" is true, then the user can change the state (color) of the die between On-wafer die and Selected Die
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If I use the sub-VI by itself, it works fine. However when I use it as a sub-VI in the tab "Wafer Map", the map does not build up and I can no further use the embedded functionalities in the sub-VI.
I suspect the while loop + event structure of the sub-VI to be the bottleneck here.
However I don't know which way to go, that's why I'd be glad to have some advice and help here.
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Solved!
Go to Solution.
Attachments:
Control Interface.zip ‏61 KB

Hi NitzZ,
Thank you for your reply.
I tried to save the VIs in LV10, please tell me if you can open them now.
Inside he event structure there is quite some code, and since I don't want to make the main vi too bulky, I would like to keep it as a sub-VI.
As you can see from the sub-VI, the event structure is used for extracting cursor position and tracking the double click action. These events are linked, through a property node, to the image "Wafer Map" which is passed to the main vi through connector pane.
All values are passed this way as well (through connector pane). Is there another way?
Maybe "refnum", but I don't really understand how to use them...
If I use the event structure in the main vi, the wafer map is still not working. I tried it earlier.
To implement the multi tab front panel, I used a tab control, and a for loop + case structure. For each element of the case structure, there is a corresponding action.
For the case where I put the code (element=2) for Wafer Map, I also control the execution of the code with a case structure activated by the button "REFRESH". Otherwise I end up with a freezing of the panel right after the start.
I hope these comments help you understand better.
Regards,
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Control Interface.zip ‏104 KB

How can I reset the value of an indicator in a while loop, from another synchronous while loop?

I am running 2 synchronous while loops, one which is keep track of time, and the other is measuring periods. In the while loop that is measuring periods, I have a boolean indicator displaying whether the signal is on or off. My problem is that when the signal is off, the VI I use to measure the periods is waiting for the next signal, and displays the boolean value from the previous period measurement. While this VI is waiting, I want the indicator to display false and not the value from the last iteration of the loop.
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Two things you can try:
In preface to the first, the most common (perhaps ONLY) use of local variables should be in transferring data between parallel loops. This is a matter of discipline, and creates programs that are easier to understand, take less time and memory, and are just plain cleaner. Having said that, to transfer data between loops, use a local variable.
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Hello,
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Thanks a lot

Hi macarel,
just proceed
You should ask yourself: Which front panel control? Is it intended to be used in the subVI?
Best regards,
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Hi, need a little help in the respect to while loops. Basically i have a while loop within an while loop within another while. So what i want to do is run the program within the outer while loop. The problem is that when i start the program it runs once, which is ok, but its the runs again and again and again. I need it to only run once untill i press the inner while loop bolean to set it going and to stop and to restart, but i can not manage to keep the inner loop from initerating. I just wonder if its a problem with the field point? because i know it works, but using a different example. Any help greatly appreciated.
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examplealib.llb ‏199 KB

Use case structures around your middle and inner loops tied to the booleans you want to control the loops. Inside each loop, use a local variable of the boolean tied to the continue terminal of the loop.
You need to use local variables because an input to a loop (wired from outside the loop) is read only on the first loop iteration. Any subsequent change to a control terminal outside of the loop is not seen by the loop.
To create a local variable, on the diagram, right click on the terminal of interest, then select Create >> Local Variable. Then right click on the local variable and select Change to Read.
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Time not stopping with while loop

Hello,
I've attached my VI. I am having trouble with while loops.
I want to turn on LEDs. The first LED should turn on after 3s. The second LED should turn on after 5s. The third LED will turn on later.
The LEDs turn on based on the following conditions:
Case 0: numeric control > 10 then led_1 off, led_2 off, led_3 off
Case 1: numeric control <= 10 then led_1 on, led_2 on, led_3 on
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Because of the way I'm delaying time, I have the following problems
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Putting probes in certain areas leads me to believe that these problems are due to the way the time delay is being generated.
Thanks in advance.
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Attachments:
timing.vi ‏15 KB

One of the problems is that your VI is not able to "breathe" because it is sometimes trapped inside inner loops that consume all CPU and step on each others toes. All you need is an single outer loop and a few shift registers.
May of your specifications are still not clear, for example what should happen to LED 1&2 in case #3? Should they remain in the state they are in, or should they turn off, for example.
Here is a simple rewrite that spins the outer loop at a regular rate, has no inner loop, and does not need any local variables or value property nodes. See if it makes sense. Also note that your code can be simplified dramatically by using arrays. Since the stop button is read with each of the regular interations, we don't need to worry about sequencing.
Most likely you need to do a few simple modofications, because your specs are not clear.
LabVIEW Champion . Do more with less code and in less time .
Attachments:
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Iteration non sequencial with While Loop

I've a SubVi in while Loop. Iteration n+1 will execute when Iteration n finish.
Can I execute this SubVi in paralel (no sequencial)?
In Spanish:
Tengo una SubVi dentro de un bucle while. Pero este bucle actúa de forma secuencial. No se cargará la iteración n+1 hasta que la n acabe.
¿Cómo puedo hacer para que se ejecuten las iteraciones de forma no secuencial? Es decir, que no haya que espera a que acabe una para que se ejecute la siguiente.

Hello,
it is not possible. The while loop works as follows: 1) execute the code inside 2) check the ternimation condition 3) depending on that, continues with the following iteration or exit from the while loop. So, it is not possible what you are asking for.
Maybe you have to use two while loops.
Regards
rusC

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nichts wrote:
Hello,
How can I do a time with while loop?. I want to read a data in the While- Loop for 1 sec and then go to B .. I added a pic,
I would use as GerdW has mentioned,"elapsed time.vi" in a statement 1st case structure, after set time has elapsed> goto 2nd case structure. try not to use flat sequences....this can be done with case statements with transitional coding. I have noticed young LV programmers like to use flat sequences...I think it's a trap set up by LV developers?

How can I to control any element of my GUI from another class?

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GameObject[] theArrayInQuestion;
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void methodWithLoop() {
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Probably simple problem with while loops

I was programming something for a CS class and came across a problem I can't explain with while loops. The condition for the loop is true, but the loop doesn't continue; it terminates after executing once. The actual program was bigger than this, but I isolated my problem to a short loop:
import java.util.Scanner;
public class ok {
public static void main(String[] args){
     Scanner scan = new Scanner(System.in);
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Thanks, that worked.
I think my real problem with this program was my CS
teacher, who never covered how to compare strings,Here's something important.
This isn't just about comparing Strings. This applies to comparing ANY objects. When you use == that compares to see if two references refer to the same instance. equals compares objects for equality in the sense that equality means they have equal "content" as it were.

Break out of a while loop from outside the loop

Hello,
I have an application where I have some nested while loops. Is it possible to break the innermost loop from a control that is outside of the inner loop? My inner loop is running a scan and read operation on the serial port and is reading data as it somes in. I need this loop to break when the user presses a button located in one of the outer loops so that another section of the vi can execute. Thanks in advance.
Greg
Gregory Osenbach, CLA
Fluke

Greg,
You should place the terminal of the button in the innermost loop and wire out from there to the other locations the value is needed. If these are nested loops, the controls will not get read until the outer loop iterates again and this can only happen if the inner loop has ended anyway. Thus your scheme will not work.
Alternatively, you can place the control in a loop that executes in parallel,then use local variables of it in the other locations, but the above solution is better.
LabVIEW Champion . Do more with less code and in less time .

Problems with opening file with while loop

Greetings everyone,
This is probably a quick question, but I am familiarizing myself how to open data files in Labview. The attached code works if you enter a file from the folder button on the front panel. However, if the path is blank and you hit the run (arrow) button, a dialog box comes up and asks for the file.
I select the file, but the dialog box keeps coming up. I think this has something to do with my while loop. Can anyone tell me where I am going wrong?
Thanks!
TheLT
Solved!
Go to Solution.
Attachments:
ReadingfromData.vi ‏27 KB

TheLT,
1. crossrulz was right. The Read FromSpreadsheet File.vi opens and closes the file each time it is called. If no file path is present at the input when it is called, it will pop up a file dialog.
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Problem with while loops, please help!

I am having quite a bit of trouble with a program im working on. What i am doing is reading files from a directory in a for loop, in this loop the files are being broken into words and entered into a while loop where they are counted, the problem is i need to count the words in each file seperately and store each count in an array list or something similar. I also want to store the words in each file onto a seperate list
for(...)
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Don't try to construct complicated nested loops, it makes things a
tangled mess. You want a collection of words per file. You have at least
zero files. Given a file (or its name), you want to add a word to a collection
associated with that file, right?
A Map is perfect for this, i.e. the file's name can be the key and the
associated value can be the collection of words. A separate simple class
can be a 'MapManager' (ahem) that controls the access to this master
map. This MapManager doesn't know anything about what type of
collection is supposed to store all those words. Maybe you want to
store just the unique words, maybe you want to store them all, including
the duplicates etc. etc. The MapManager depends on a CollectionBuilder,
i.e. a simple thing that is able to deliver a new collection to be associated
with a file name. Here's the CollectionBuilder:public interface CollectionBuilder {
   Collection getCollection();
}Because I'm feeling lazy today, I won't design an interface for a MapManager,
so I simply make it a class; here it is:public class MapManager {
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   // constructor
   public MapManager(CollectionBuilder cb) { this.cb= cb; }
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         map.put(name, c); // and associate it with the filename
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   // get the collection associated with a filename
   public Collection getCollection(String name) { return map.get(name); }
}... now simply keep adding words from a file to this MapManager and
retrieve the collections afterwards.
kind regards,
Jos

Need help with while loops

Hello let me first explain what im trying to achive:
I want a moving square that you control with the arrow keys on the keyboard. It has to be smooth ie able to move fast without looking like its jumping and it has to be able to move diagonaly aswell. Think of that arcade game Raiden ...you know the birds-eye view plane flying game...another thing! I'd prefer if it didnt use timers - i made one already using 4 timers and it works great but 4 timers is a little extreme - SO NO TIMERS !
I was thinking while loops, but i cant seem to get it working. I dont want to put in all the code so ill just say that I have 4 booleans: up, down, left right and the following code:
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_UP) {
up = true;
if (e.getKeyCode() == KeyEvent.VK_DOWN) {
down = true;
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
left = true;
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
right = true;
repaint();
For the KeyReleased part i have the same as above exept it sets the booleans to false.
Soooo in theory if i set up a while loop like this (using the up direction as an example) :
while (up == true) {
[move square up]
So therefore when i press and hold the up arrow the loop will keep going untill i realease it right? WRONG ! it just keeps repeating indefinatly and it doesnt even do the " [move square up] " bit. I put a System.out.print in the loop to test and it kept printing out the message but it still didnt do the actual " [move square up] " bit.
Im not sure if im putting the while loop in the right place either....If anyone has any idea on how to use while loops in this way please heeeelp ! Its so annoying because it just doesnt work ive tried so many ways...
any help would be greatly apreciated !!!!

Maybe you want something like this? You have to pause during the loop to allow for other events to happen, like if y ou release a key or whatever.
while( true )
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}

Controlling a SubVI with while loop from another VI

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