Event structure in a subVI

I know this problem has been posted, but I've already am passing everything by reference. I can't get my subVI to respond to my top layer VI. It runs fine as a stand alone, but when I ask it to monitor events from a reference, it won't do anything. I've attached what my sub VI looks like. My goal is to have the the event structure respond when a new file path is sent, stop button pressed, or a enum is changed. The subVI is called Read Track shown in the top VI with all the references passed.
Top VI
Message Edited by d1sturbanc3 on 02-27-2008 12:30 PM
Message Edited by d1sturbanc3 on 02-27-2008 12:31 PM
Attachments:
event.JPG ‏163 KB
top event.JPG ‏301 KB

You should use dynamic events.
Your SubVI with the event structure should run in parallel with your main code.
What you currently have will never work.
Here's an idea of how the subVI should look like:
Try to use the Code Capture Tool to get images of your code...
Good luck,
Ton
Message Edited by TonP on 02-27-2008 07:45 PM
Free Code Capture Tool! Version 2.1.3 with comments, web-upload, back-save and snippets!
Nederlandse LabVIEW user groep www.lvug.nl
My LabVIEW Ideas
LabVIEW, programming like it should be!
Attachments:
PathEventChange.png ‏5 KB

Similar Messages

Can I use Event structures in a subVI?

Hi,
I have a subVI (ProvaEv1.vi) that use an event structure inside. But when I use it in a VI (ProvaVI.vi) the event structure in the subVI doesn't catch the events.
I tried to insert the event structure in a while loop but it doesn't work too.
Could you help me?
Thanks Ius
Attachments:
ProvaVI.vi ‏11 KB
ProvaEv1.vi ‏15 KB

"iusn" <[email protected]> wrote in message news:[email protected]...
Thanks to all for your answers!
Wiebe! I tried to do as you suggested but I am not able to link the Event Reference Number inside te SubVI with the Event Register Number of the Register for Event in Main VI. There is e class conflict. Another question: how the SubVI can know the structure of the Register event outside?My aim was to create a modular structure but it seems very difficult, wath do you think about these problems?
The broken wire is related to your question. The event structure inside the sub vi knows about the events you register in the main, because the reference wire/control has a "strong" type. It contains information about the registered events. That is also why the wire is broken. You have to register all events, then create an indicator/control of the output. Use that control in the subvi. You have to do this every time the events change (you might use a type def if you use the control a lot).
Usually, the events that you would want to put inside subvi's are those related to user interface objects. I've had this a lot. You make a nice interface, but it's not reuseable, because the events are mixed with all the other events. Only solotion is to manually add the needed event cases in your program, and copy the code.
Even if you can put the events in a sub vi, I'd expect hanging vi's when more subvi's are registered for the same event. It's hard to tell without trying. So it's not a real solution either.
Like Chrisger suggested, the event callback might help a little, but they are tricky, and actually ment for this (they are intended for activex callbacks).
Perhaps you should look at XControls (if you use 8.2). It would be more work to replace your code to XControls, but once you're done, you have reusable code.. Haven't worked with them jet, but they are invented for this problem...
Regards,
Wiebe.
I have already create my application using event structure just in Main VI but it seems very complicate to read and keep update, I would have wanted to give modularity to my application.
Thanks Ius
SubVIEventMain.vi:
http://forums.ni.com/attachments/ni/170/203225/1/SubVIEventMain.vi
SubVIEvent.vi:
http://forums.ni.com/attachments/ni/170/203225/2/SubVIEvent.vi

How to use a event structure in a subVI

I am trying to use an event structure inside a subVI. The subVI has an array builder that builds arrays, and the event structure is used so that when the program is running, it allows you to change the elements of the array. It works, but when I implement it inside a subVI, it does not work properly. This is going into a subVI, because it will be a part of a much larger progrram, so it needs to be modular.

If you're using an event structure, it's not a subVI. if you're worried about modularity, you shouldn't be using the event structure.
You seem to have a fundamental misunderstanding of modularity. An event structure should be placed within a while loop. If you have a while loop within a subVI, you've handed over control of your program to the subVI. You're not modular at this point. Your top level GUI has no control. You'd have to create some asinine system of variables to pass data down to that loop to stop the loop and return to your main VI. That's not a good design decision.
Instead of looking for a way to do something broken, you should spend effort trying to understand what you actually want to accomplish. You should also spend some time learning how event structures work.
This application is small right now and it's already on the path to unreadable. That's a terrible thing to do to yourself. Break these habits now. se variables only when absolutely necessary. Use subVIs to accomplish individual tasks, not run the entire application. With event structures, use a stop button value change event to not be held hostage by the timeout. If your variable has "2" in it, you're doing something wrong. There has to be something different between the setpoints, put that in the name. If you want to make subVIs, create an icon.
But first and foremost, invest time in understanding dataflow

Handling event structure in subvi

I go through fierce problem for using event structure in subvi.
Main VI contains event structure in a SubVI
Event structure is composed of two event. one is "Time Out" , the other is "Value Change".
What I want for this VI is Time out event works without a delay time , except of case of Value Change event
But "Value Change" event of this VI is not working properly. Even when Value Change event is working , "Time Out" event is still working.
To explain in more detail, When Value of Boolean is changed , ligh of Boolean Out must turn on.
Please, help me.
Attachments:
example.zip ‏14 KB

Hi,
Have a look at the attached vi. your value change event is working properly but once after that event is fired it will be going to timeout there we are sending false to the boolean hence your not able to observe the value change occured.
Attachments:
main vi Folder.zip ‏9 KB

Trigger Event Structure in SubVI

Here's my goal. I have a VI that sets two analog outputs which in turn control a power supply. One output controls voltage while the other controls Current Limit. I created a VI which uses an event structure so that when the voltage or current limit is changed, the analog outputs are adjusted accordingly.
Now, I'd like to turn that into a SubVI and have it running in the background while my main VI runs. I'd like to be able to go into the subVI and change those values at certain locations within the main VI. I tried just using the subVI with register events, but it hangs because it is waiting for the subVI to finish before continuing. I tried using the Run VI methond with "wait until done" set to false, but then I don't see how to trigger my events because I can't link my mainVI to the events that need to be triggered. I can set the control using Control Value Set, but that doesn't do anything for my event structure and thus stuck again.
Maybe the event structure isn't the best way to do what I'm seeking. But I don't want to set all this up in my Main VI because it just adds too much complications and I already have the VI working by itself and just want to turn it into a subVI.
Thanks.

You could either get a reference to the SubVI and find the specific control like the attached picture, or you could pull the SubVI out of the main loop. If the SubVI is necessary for data flow, you are almost certainly going to have a hang up if you don't call it by reference.
edit - Another, probably less popular, option would be to have the subvi running in a parallel loop and have locals take data from the control loop and write to the command loop. You'd have to be careful to only have one local writer, though.
Message Edited by JeffOverton on 01-30-2008 02:39 PM
=============
XP SP2, LV 8.2
CLAD

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.
To start with I provide you with a simplified version of my control interface VI, and with the sub-VI used to build and manage the wafer maps.
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)
3/ display the coordinates and index of the die below the cursor
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
My issue:
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.
Thank you.
Florian
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,
Florian
Attachments:
Control Interface.zip ‏104 KB

How to make Vi file as input file in Event structure?

Hiii All..
i got problems when to construct a event structure. The file input (vi format) doesnt have source of wire connection to conect the wire (shift register) .For your information the vi that i create only contain simple mathematical equation.
I already study the New Event Handler Example. but the file input for that example (acquire data.vi) have a source of connection. anyone can help me?
thank you very much
[email protected]
Solved!
Go to Solution.
Attachments:
TOTAL.vi ‏18 KB

Well, in your subVI you do need to wire up some inputs and outputs to your connector panel. As I said, a basic LabVIEW skill that you will find in the tutorials.
You have a number of inputs to your subVI. More than you would want to attach to a connector panel. You should perhaps use a cluster to group them together.
To get you started, here are the steps to connect a control or indicator to the connector panel.
1. Open subVI.
2. Right click on icon at upper right. Show Connector.
3. Hover over a block you want to be a connector terminal, it will change to a spool of wire. Click.
4. Go to the control or indicator on the front panel that you want to associate it with. Click again.
5. Repeat as needed for other controls and indicators and save your subVI. Now the subVI instance in your main VI can have wires connected to it.
You should plan your connector panel so that controls are on the left side of the panel, and indicators on the right. This will allow data to "flow into" and "flow out of" the subVI in a normal looking left to right orientation.

How to use a event structure with a state machine

First, I would like to inform you that I only work on LabView part time, and have much to learn. Anything I do learn, I usually forget until I need it again, because I only work on it part time.
Using your StopWhileLoopMOD[1].vi, I am trying to put a state machine inside the event structure.
Related link: http://forums.ni.com/t5/LabVIEW/How-to-stop-while-loop-in-Event-case/td-p/465564/page/2
Here is my application: on the front panel, the user can select any combination of 7 different tests. I have created cases to perform each step of each test in the correct order, but if the user presses stop, the tests won't stop because some of the cases have a while loop inside the event structure (like you mentioned is a bad idea). The user should be able to stop the test, reselect tests to perform, and re-start the tests.
When the start button is pressed for the event structure, I need all the cases to run in the proper order, unless stop is pressed.
In the past I have indexed an array and used that to run the state machine, but it won't stop immediately.
I have sub VIs that are built in while loops because the outputs of the product needs time to stabilize.  The state machine stops and waits up to a certain number of iterations. If it passes the test, the while loop stops and the next state starts. If it takes too long, it exits and reports an error. Maybe I need to just use the state machine and not an event structure?
Is there a good example of an event structure?
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.
Hope this helps.
A
Attachments:
mainvi.vi ‏17 KB
subvi.vi ‏33 KB

How to use an Event Structure responding to an image control that belongs to a parent VI.

Hi
I am loading a subpanel vi by pressing a button located in the user interface of the main vi which also contains an image display. Subpanel vi opens up on the side and doesn't hide the image display of the main vi. Subpanel vi contains an event structure that needs to respond to user clicking on the image display of main vi.
Since the bug that occured while creating an image reference control isn't fixed, I am passing the main vi pane reference onto the subpanel vi. From that point I've tried to edit event structure and have it respond to the image control/pane that belongs to main vi but I don't know how.
Any help would be appreciated.
Thanks

Post a screenshot of your subVI code where you register the events.
André
Regards,
André
Using whatever version of LV the customer requires. (LV5.1-LV2012) (www.carya.nl)

Can I get the event structure to NOT queue events?

I was wondering if it is possible to have the event structure not queue events that happen while the vi is executing code associated with another event. Basically, I have a toggle switch that, when "on", captures a live feed from a camera and displays it to the screen. This is done in a while loop that executes until the toggle switch is turned off. At this point, that event is done and the vi returns to the uppermost level of the event structure and resumes looking for events. The trouble is that the whole while the video capture was happening, the event structure was queueing events that were occuring during that time when the user was hitting other front panel buttons that had their own event associated with th
em and would not execute at that time. When the video capture toggle is turned off the event structure then executes any other events that were queued during that time and I don't want it to. I can't lock the front panel while the video capture is happening so the user can't push buttons because they have to be able to push the button to turn the video capture off. Any suggestions? Thanks in advance.

> I was wondering if it is possible to have the event structure not
> queue events that happen while the vi is executing code associated
> with another event. Basically, I have a toggle switch that, when
> "on", captures a live feed from a camera and displays it to the
> screen.
I think there are lots of other articles about this on devzone.
To summarize them, the key is that the event structure intentionally
synchronizes events with diagram execution. The typical way to do what
you want is to have the event start up another loop or subVI running
asynchronously.
Usually there ends up being one loop with an event structure in it.
Another loop that executes a statemachine, possibly as simple as just
two states of acquiring and not. Use the events to pr
od the other loop
between states via locals, globals, occurrences, etc.
Greg McKaskle

How to stop a while loop of event structure from a main vi

Hello;
sorry for my english
I have to stop a subvi from my main vi, the subvi contains a while loop and an event structure so I need to stop this loop while directly from my main vi I have tried global variable but it did not work
any help please or example !!!
Solved!
Go to Solution.
Attachments:
stop a while loop and event structure from main vi.png ‏16 KB

IYED wrote:
Hello;
sorry for my english
I have to stop a subvi from my main vi, the subvi contains a while loop and an event structure so I need to stop this loop while directly from my main vi I have tried global variable but it did not work
any help please or example !!!
If this is an example of how your code looks, I'd clean it up before the developer who has to work on it next hits you over the head with his LabVIEW Style Book.
Bill
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.

Event structure to detect value change of a control within a cluster in an array

I have 1D array that contains a cluster. The cluster contains a numeric and a boolean control.
If the user starts to edit the numeric control value i would like to call one subVI, and if the boolean control value is changed, call a different subVI.
The array control on the front panel allows the user to edit a number of the array elements.
I would like to use an event structure to detect a value change in the cluster. When editing the Events, in the Event Sources panel i get the option to select only the array, not the cluster within the array or the controls within the cluster. Can the Event structure be opened up to show controls within clusters and arrays?
The solution i am using is to detect a mouse up event on the array and then use property nodes to determine if the key focus is on the numeric, and a case structure to determine which subVI to call. This works, but is there a better (simpler) way?
Thanks, Blue.

Thanks for the responses guys.
The tricky bit was that i wanted the numeric control values to flag they were going to be edited, so i could call a subVI, before their values were changed by the user. This is done by using the key focus property node, - i need to detect changes on the fly rather than post the event. Probably didn't make this clear enough in my original post.
The array is of variable size depending on if the user decides to insert or delete elements. The user also has the option to click and edit the array without having to do to much scrolling through the array index, as the FP shows several elements at a time. The Event Structure does a good job of automatically determining which element in the array is being edited, and returning those values to the property nodes. Turned out simpler than i thought it might be at one point!
Cheers, Blue.
Message Edited by BlueTwo on 01-15-2009 06:52 AM
Attachments:
evstrct1.jpg ‏63 KB

Event structure freezing when short delay inserted

Well, the simple stuff in LabVIEW I can do, but I'm still struggling to get my head around the concept of "Events" and how LabVIEW handles them. If I only have one type of event (i.e., pushing a button out of several on the UI, or reading a serial input and handling it programatically), I think I'm good. But my application requires me to be able to handle either of these at the front panel.
Going through the LV Knowledgebase got me this link (it's a little old - LV8.6, but seemed to handle the basics), from which I downloaded "events.vi" (attached). My situation is a little different, so I modified it a bit to "EventExperiment.vi" (also attached) to have a bare-bones template I could use for my application. If I run it as shown, it seems to run fine (with a serial input, the "1" and "2" lights turn off, but the Bytes at Serial Input indicator always shows "0" and the "Serial Indicator" light never lights - I am assuming that these change and revert too quickly to see in the UI). My concerns with my VI are:
If you add a short delay in the processing of the serial input event (say 1 second delay in that event case, or even a 1 second delay subVI after the serial flush connected through the error line), the VI accepts no further UI input after the first serial event.
If you add an error wire through all the events subVIs (whether you merge this wire with the one going through the serial subVIs, the program just hangs up.
And, one little bothering thing is that the original "events.vi" takes three presses on the "stop" button to close. I'm figuring here that it's because of those local variables being passed between loops, but it hasn't been enough of a bother to worry about.
Your help is greatly appreciated,
Cameron
To err is human, but to really foul it up requires a computer.
The optimist believes we are in the best of all possible worlds - the pessimist fears this is true.
Profanity is the one language all programmers know best.
An expert is someone who has made all the possible mistakes.
To learn something about LabVIEW at no extra cost, work the online LabVIEW tutorial(s):
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Attachments:
events.vi ‏24 KB
EventExperiment.vi ‏25 KB

Well, I thought I'd add a final post for some closure to this one.
To summarize what I was trying to accomplish: I wanted to have some kind of an event structure where you could use both regular User Events (button pushes, numerical control changes, etc.) and an outside (non-keyboard/mouse/touchscreen) event, like a serial character coming into a COM port, to initiate an action. This was to eliminate a loop where the computer would be polling the COM port continually at a pretty fast rate. (I must have read a hundred times in the past month that you don't want to run a While loop for polling if you can help it.)
It turns out (after a couple of confusing days, I talked with the NI service engineers) that you can't do this. In order to detect a character at a COM port, you have to be polling the port periodically with a Read and look for a change in the bytes available or another parameter. You can do this through a timed loop separate from your Event loop or through a Timeout event case inside the loop, like Don_Phillips suggested.
However, I believe I'll go the separate loop route, since my head's actually more comfortable with it than the Timeout route.
Thanks, folks, for your help,
Cameron
To err is human, but to really foul it up requires a computer.
The optimist believes we are in the best of all possible worlds - the pessimist fears this is true.
Profanity is the one language all programmers know best.
An expert is someone who has made all the possible mistakes.
To learn something about LabVIEW at no extra cost, work the online LabVIEW tutorial(s):
LabVIEW Unit 1 - Getting Started
Learn to Use LabVIEW with MyDAQ

Pop-up in event structure halts execution

If I place a pop-up subVI in an event case of an event structure and this pop-up subVI contains a while loop and a stop button that would stop this while loop (thereby closing the subVI), will other events declared in the event structure be handled only after the user clicked the stop button of the subVI? If yes, is there a way for other events to be handled while the pop-up subVI is still running?
Solved!
Go to Solution.

Yes, it will stop everything in you rmain VI until the popup VI returns. The events will still be buffered, but they won't be handled by the event structure, until your pop up is closed (assuming your pop up is non-modal). If it's modal, the user won't be able to click anything at all, except controls on the pop up itself.
If you still want the user to be able to interact with your front panel while the pop up is showing, and have the FP respond, you will want to launch the popup dynamically in its own parallel process. If you are using LV 2012 you can use the start asynchronous call node. If you are using an earlier version of LabVIEW, you will have to use the "Run" method with an invoke node.
CLA, LabVIEW Versions 2010-2013

Query regarding event structure

I have created a program as follows.
For the 2nd event I just need to replace the data in the array which is attached to VISA write.
My question is do I need to create a event again and again or is there another way out.
I am new to LABView.
Please Help.

If all of your event cases will be the same except for the array constant, turn all of that inside a subVI and put it outside of your event structure. The idea here is that the event structure just passes out the data to send.
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Event structure in a subVI

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