Event structure capture event on dimmed buttons

Hi,
I have a MMI with buttons I dynamically disable or enable by means of Property Nodes. I capture the Release Mouse Button Event on these buttons with an Event Structure. The problem is that my application seems to recognize this event even when the buttons are disabled and greyed out... What am I doing wrong? Is this a LabVIEW bug? What can I do to prevent this from happening?
Thanks

This is the expected behavior: disabling a control prevents the user from changing its value (and other attributes for compound controls like graphs), but does not prevent the control from receiving mouse events.
You may want to test for a disabled state and filter the event, yourself.
Good luck,
-Jim

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Event structure misses events

Hi,
I've got an event structure with events reading all my inputs, and one dynanmic event running every 10 ms. The dynamic event is a pretty heavy piece of code.
It works swell, except that sometimes the events generated by inputs from the front panel are ignored. Is there a way around this? A screen shot of my code is attached.
Thank you!
Christopher
Attachments:
events missing.png ‏69 KB

This suggestion is based on partial information and a picture so apologies if this is not relavent.
I would change your structure with queues, it looks like you generate a notification every 10ms. You could replace all of this with a single consumer loop which essentially is a dequeue loop with a 10ms timeout and do all of the dynamic event processing when the dequeue times out. You can also enqueue any front panel activity to the same queue in the event structure. Look for producer consumer examples, it is very elegent
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Calling a VI in a subpanel with parameters inside an event structure and using an abort button

Hi all,
I have a control panel with a tab control and two tabs have a sub panel in them. At runtime I load the VIs I want in to the sub panels. In the control panel event structure I want to start each of the VIs and monitor the execution state so I can abort the VI while it is running. One method I use can run the VI and the abort event will work (see example). The second method I use does not and this is what I want to do! I have many inputs to the VI I want to pass so placing the VI in the event blocks everything else and it has to wait until the VI has completed, so I cannot monitor the execution state.
I have attached an example of what I want to do.
Any help appreciated.
Martin
Solved!
Go to Solution.
Attachments:
SubPanel.lvlib ‏2 KB

Hello,
You can do this with queues.
The main vi and subpanel vi's should be based on the producer/consumer (events) and you handle the front panel events accordingly in the respective vi's.
Name the queues in obtain queue , for example the Main being MainQ, subpanels SubPanel1Q, SubPanel2Q. When you start the application, initialise the main vi and also run both of the subpanels (just to make sure that the queues are first obtained by themselves). Then you can use obtain queues to do inter vi communication.
For example if you need to send data from main to subpanel1, use obtain queue and use the name SubPanel1Q, pass the required data & command and voila. Subpanel1 vi will receive your message. You can do this anyway you want. Hope this helps.
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Event Structure with Event source: This VI and Event: Mouse Up

I downloaded an old example from 2008 on this forum and would like to duplicate it. It uses an event structure with an event case of just Mouse Up. Under Event Specifiers: the Event Source is <This VI> and Event: Mouse Up. This works like I want in LV 2009.
In LV 2009 if I choose for Event Source <This VI> under Events Mouse Up is not an option! I tried Event Source: Pane, and then Event Mouse Up is an option, but this does not trigger the event if you drag the mouse off the pane before you lift the mouse button.
I can copy the Event Structure over to my VI and rewire every case but that does not seem to be a good solution cuz I want this in several VIs.
I have attached the original VI with the Event Specifier I want. How do I get this Event Specifier in LV 2009?
Attachments:
Slider event control.vi ‏19 KB

phillman wrote:
I downloaded an old example from 2008 on this forum and would like to duplicate it. It uses an event structure with an event case of just Mouse Up. Under Event Specifiers: the Event Source is <This VI> and Event: Mouse Up. This works like I want in LV 2009.
In LV 2009 if I choose for Event Source <This VI> under Events Mouse Up is not an option! I tried Event Source: Pane, and then Event Mouse Up is an option, but this does not trigger the event if you drag the mouse off the pane before you lift the mouse button.
So what you can do is monitor the 'Mouse Leave' event for th pane, and then start polling the mouse state.
Technically it is correct that there is no Mouse Up event detected since the Mouse Up is not happening on th epane.
Ton
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Resetting a variable in an event structure (dynamic event)

I'm working on moving an event structure into a sub VI. This means I have to register dynamic events.
The event structure is handling some button clicks. The state of the button (mechanical action = latch when released) resets itself automatically as long as the variable is placed within the value change case. Leaving the button in this case is not possible when the event structure is put in a sub VI and the variable is located in the parent VI. How do I make sure the button unlatches after clicking on it? I have attached an example where all the code is in one VI (the local variable must be moved outside the event structure in order for it to be moved into a sub VI). Any ideas?
If you open the VI and run it, you can click Start which will cause the counter to start incrementing. The button only unlatches as long as the variable is located in the value change case.
(Btw, how do you put images inline in a post?)
Rob
LV2011,LV2012,LV2013
Attachments:
img.png ‏18 KB
main.vi ‏17 KB

Race conditions are the primary reason not to do that. But since your treating your variable as a latch, I doubt your using the value you read from it anywhere, and in that case it can't create a race condition. There's also the possibility that the control's reference could become invalid. But since this is a sub VI of the control's VI that can't happen (even if it could you can check the error out of the value property node to see when it happens and deal with it).
I'm not sure about the flickering, Since I can't seem to duplicate it with a simple test case on my machine. It might related to whatever else you're doing in the event apart from reseting the value to false.

Event structure input event question

I'm using a state machine to do some data decoding stuff. The default initial state is Idle, which checks an output boolean value from a FIFO buffer. If the boolean value is True, go to the next state; otherwise, keeps waiting. See attached "idle_noEventStructure.vi" for part of the code. But this method will consume a lot of CPU usage.
In order to save CPU time, I try to use an event structure in Idle state to wait for the output boolean value change. But I don't know how to add an event for the boolean value change. See attached "idle_eventStructure.vi".
Any one could help?
Thanks.
Attachments:
idle_noEventStructure.vi ‏7 KB
idle_eventStructure.vi ‏8 KB

MileP,
First off, in the state machine example you give "idle_noEventStructure.vi" the reason you may be experiencing poor performance (high CPU) is that your while loop is running as fast as the OS will allow sicne there is no timing implemented. You should always you a "wait" function inside the loop (see attached file). The loop should only run as fasat as you need to check the FIFO for new data.
If you want to use an Event structure you can use dynamic event registration to create an event for the FIFO data. I have outlined this in the attached code. It may not be eactly what you need but should give you he right idea. An event is created for the boolean output from the FIFO and this event is registered with the event structure. I am simulating the FIFO data using the "Producer Loop" and the Trigger control. I am simply stopping all the loops when the Trigger button is pressed, but this is done using the event creation. This method still requires a polling loop ("Consumer Loop" in my example) to check for FIFO data, but the lopp rate can be handled more carefully this way. And I am not sure there is anyway around using some method of polling.
Dan
Attachments:
Event Registration.vi ‏17 KB

How to use event structure of event data nodes event filter nodes in programming

hi,
I need manual of how to use 'event structure' events of 'event data nodes' and 'event data filters'...please help me....
Regards
Ravindranath

I'm not really sure what you are looking for here. Did you do a search in the LabVIEW help for Event Structure?
The Event Data Node just returns information about the event, like control data, control reference, what caused the event, etc.
The Event Data Filters are just used in Filter Events. This allows you to discard an event or change the data that the event will recieve.
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Event Structure - Lock Event: Does it Queue ?

I had couple of question related to this post in other posts but I thought I'd use a new one since it might be more relevant (others were related to local variables, and VI file sizes)
I have this event structure running about 10 different tasks. For some I would like to lock the panel when it runs. I used "Lock panel ..." but during the run, if you click on any boolean and menu ... for some reason it queues the task and performs it after the event is complete ... is there any way I can lock the event and not have any event queued ? Thnks !
Kudos always welcome for helpful posts

If you were to change the value of the Block Panel Event boolean using a local variable it wouldn't fire an event so I'm not sure that would be the way to go. I had intended that just to be an example control.
I have further modified the example to show how a custom user event can be programatically fired to signal that the front panel should be "unlocked" and that new events should be added to the event queue. In the new example you will see that while the LED is flashing no events are queued. Once the LED is done flashing it communicates to the event structure via a user event.
It may also be possible to change the value of the "locked?" boolean without requiring an event to do so. I didn't explore this option but it may be a valid approach.
Also please remember that any example I have posted here is not meant to be incorporated into an application - I am merely attempting to demonstrate ideas and concepts. It will be more beneficial for you to examine and understand how I programmed a certain behavior and then use those concepts to create your own application than to try to make my code fit into your application.
Regards,
~ Simon
Attachments:
lock event 2-1.vi ‏75 KB

Event Structure: Multiple Events ??

All
I have a project where I have an event structure handling about 10 individual events. Would it be possible to fire multiple events at the same time ? For instance, if my event 3 is triggered and the corresponding process is running, can I trigger an event 7 to have it's process running ?
Kudos always welcome for helpful posts

Edit your event and make sure to uncheck "Lock front panel until the event case for this event completes", else you won't be able to do much.
Attached is a simple example using two event structures. (All that said, maybe there is a better solution than using two events, just re-think your code).
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Attachments:
2events.vi ‏42 KB

EVENT structure remembers events from previous call?

LV2013, Win7
My customer has complained about this misbehavior, and I made a basic VI to show it. No one noticed this behavior in LV 7, 8, or 2010.
Given a SubVI with a RETURN button, that is set to SHOW FP WHEN CALLED and CLOSE IF ORIGINALLY CLOSED, then we have what seems to be a misbehavior by LabVIEW.
The SUBVI is normally closed. If you run the TEST vi and click the DO IT button, the subVI comes up.
If you click the RETURN button TWICE, during that five-sec interval, the button sticks in the DOWN position. I understand that.
When the timer expires, the window closes. I understand that.
If you click the DO IT button again, the window comes up again. I understand that.
But the window will close BY ITSELF, after another 5 seconds ! I DO NOT understand that.
Even if bringing up the window acts to pop out the button, that cannot cause termination, because termination is caused by a VALUE CHANGED event, changing to TRUE! But it does.
I tried limiting the events in the queue to 1, no change in behavior.
Attached is a test vehicle, try it yourself.
Is this a bug in my thinking, or a bug in LabVIEW?
Steve Bird
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Attachments:
TestEventQueue.zip ‏16 KB

when you define a static event, the registration for that event (that's the point where it starts queueing up events) happens as soon as the VI that the structure is in enters run mode. That doesn't mean that the VI is actually running, but rather that it is running or reserved for running. The unregistration happens when the VI leaves run mode.
OK, I understand that. Although I didn't think about it before, that makes good sense. The dynamic registration system is the root behavior, the statis stuff just supplies fixed references at RUN MODE time. Fine.
But how is it that the second call, which depends on a VALUE CHANGED event, with a value of TRUE, doesn't just get ignored?
OIC - what is queued is the original event, which IS a transition from false to TRUE.
Funny - I've used LabVIEW for 25 years and never noticed this issue myself. I guess I thought the event queue was flushed when the window came up.
So, I should use a FLUSH EVENT QUEUE at the start of every such VI, I guess. I don't want to add a time-check to every single event case.
Steve Bird
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How to handle event structures for two buttons and two counters.

     *I have two buttons A and B, and have to compare the difference in hits between them. So do I place an event structure within a while loop for each button (2 buttons, 2 event structures, 2 while loops), or does it need to be one event structure with cases for both buttons whithin one while loop?
     *How do I pass the values of buttons A and B's hit counters out of the while loop in order to calculate the differences between them after each increment, not just the final count after the stop button is hit?
    *How would I make one stop button work to handle both buttons A and B?   I tried to place the actual stop button in one button A's structure and its global in B's structure, but It wont seem to let me use a local variable for a latchable control
Checker

You should probably have not started a new thread and waited until your question in the original thread was answered. You can modify altenbach's example for a second button. You have a single event structure with a new event for the second button. You have a second shift register to track the number of times the second button is pressed. Inside the while loop but outside the event structure, you just have a subtract function in or to report the difference. do not modify the posted example for the stop button. It works perfectly as is.

While loop with stop button within event structure locks up front panel.

I am not sure if this is a bug with my program or a bug within LabVIEW. If you believe that this is a bug with my program then I will post my program to be looked at.
The problem I am having is there is a while loop within an event structure that fires when a particular value changes. Once the "Activate" button is pressed the while loop within the event structure starts going with a polling frequency of 1hz (1000ms wired to the "wait till next ms multiple" vi). There is a "Deactivate" button that is wired to the stop control of the while loop and an outter while loop that resets the event structure so that the activate button is being listened to again.
Once inside the while loop, however, none of the button are responsive within the front panel. The VI continues to run, and only 60% of my CPU is being consumed, but none of the button or scroll bars work. The only way for me to terminate the program is with the "Abort" button next to the "Run" button. If I remove the event structure so that the while loop in question runs as soon as the program starts, the front panel remains responsive. I've inserted probes within the while loop and verified that it is not running prior to the "Activate" button being asserted, and it is running after the assertion of the "Activate" button with the expected polling frequency set by the "wait till next ms multiple" vi.
Can anyone help? Do I need to post my code?
-Nic

It is typically not a good idea to stall an event structure by placing loops inside event cases. What good is an event structure if it is not free to repond to events?
Have a look at some alternative solutions, such as in the following link:
http://forums.ni.com/ni/board/message?board.id=170&message.id=224817#M224817
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Using a Global as a value change in an Event Structure

I have many events I want to react to based on Global buttons. How do I get the Event Structure to recognize a global button value change? This screen shot is one of my many attempts. So far my events only change with a real button on the FP.
Thanks in advance,
Doug
Attachments:
Event Structure.JPG ‏147 KB

nonecure wrote:
Jim,
The Value (Signaling) does not work either.
I would rather not use a notifier, so maybe I need to get away from using an event structure.
Thanks
It should work if your code was executing correctly. The image you posted...
may be the reason.
If you watch the code in execution highlighting it may help you figure what is happening.
1) There is no guarentee that "initialize" will be written to the local "State" before the loop starts running. Use a shift register to track your state from iteration to iteration.
Do you get any errors?
Ben
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While loop inside a event structure

Dear
I have no much concepts on event structure.
Let's assume there is a dialog box with Okay and Cancel button.
I put the event structure for Okay and Cancel button.
In Okay event, there is a while loop for detecting some data continuously.
In this case, I want to use Cancel button to stop the while loop during the detection.
How can I do to receive signal from the Cancel button?
Thank you in advance.

I'm not sure that the event structure should be used to handle that situation : while the OK event is executing, either the Front panel is locked and new occuring event will be stored until the OK event is completed (so the Cancel button action will not be detected !) or the Front panel is unlocked (see below *) and the Cancel button action will stop the loop, but the Cancel button event case will not be executed, since the event has already been processed in the OK case !
You should probably use a single button to run/stop the loop, as shown in the attachment
* While editing the event case, unmark the "Lock front panel for this event complete" at the bottom. But of course, the code in the cancel case will not run, since the event occuredMessage Edité par chilly charly le 03-31-2007 05:27 PM
Chilly Charly (aka CC)
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Attachments:
Event button.vi ‏11 KB

Event structure and automatic queueing of events.

I have found out the long way that the event structure queues all the events taken place while it has been executing yur most current event.
In other words... I understand why the locking of the front panel is an automatic option that is selected. As it will prevent you from queueing more events, and causing yur program to execute endless event structure runs, when you wanted it to stop 15 button presses ago.
case in point.... is in this simple VI i attached.
My question is ... is there a way to turn off this automatic queueing of events??
Attachments:
EventStructureHUH.vi ‏53 KB

Well ... the problem for me... was, for example, in the VI I posted....
The OK button in the VI I posted, has an event triggered to it in the event structure.... So when I enter that loop after hitting the enter loop button... it registers those OK clicks...
Say the OK button and NOT the continue button takes me out of the little loop and back into the big loop. Now, after leaving the little loop and entering into the big loop, I will immediatly enter back into the event structure to handle the OK button click.
Basically I wanted one button to control the termination condition of the little loop, but also have an event in the event structure associated with it, so basically one button to exit the little loop AND the big loop.
I hope Im making sense. I found a solution, by just making two buttons, when entering into the little loop, the one button dissapears... and vice versa when entering into the big loop. So to the USER it appears like ONE button... but in the code its actually two.
I just wasnt sure if there was another way around it... it was tough to figure out what was really happenening in my code... took my about an hour or two to track down.
EDIT: Yea.. thanks for the reply.... as for the comments in my code... yea, I get a little crazy towards the end of the day... after 6-8 hours of straight labview programming.
Message Edited by MJBrehm on 06-30-2006 02:21 PM

Event structure capture event on dimmed buttons

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