Canoe Event Handling in Labview

Anybody worked on handling the events of CANoe in Labview?
I am trying to handle the event when there is a value change in the environment variable of CANoe. CANoe provides a COM method "OnChange" but i do not know how to implement this method in Labview. This method is available in CANoe -> Application-> Environment->EnvironmentVariable-> then event OnChange.
Any ideas??
Thanks,
Suhas

Hello,
I'm willing to handle the same process as you, but I did not yet success. I attached my project, and I think my problem is more Labview than CANoe. If you successed or if anyone already have done such diagram with VICallback and Event Data, please have a look, I'm really fighting without success now.....
Attachments:
CANoe_Graphic.vi ‏22 KB
sub2.vi ‏12 KB

Similar Messages

Event Handling in labview with arrays as event data

Hey folks,
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However i have only managed to get this event based mechanism to send out a single structure at a time. Hence if there are 10 fresh data values, i need to send out 10 events (each event structure contains the parameter name, parameter value, unit and time stamp). It would be more efficient to send out an array of structures in a sigle shot.
I have tried this but Labview keeps crashing saying that an error was encountered and Labview needs to close along with an access violation message. I did a lot of online searching and found some LV code for event handling but not come accross any implementation which uses arrays as evend data. Is this supoorted? And if so is there any example vi that can be shared so that i get some knowledge about this.
Many Thanks in adavance,
Abel.

I also gave a try by using a variant as the event data type instead of the cluster which contains the array of floats. I converted the cluster into a variant and used that to create the user event reference. Followed the same logic while decoding the dats.
But still the crash.... Here is the windbg output...
ModLoad: 07580000 075b7000 C:\Program Files\National Instruments\LabVIEW 2012\resource\lvalarms.dll
ModLoad: 0ca90000 0cb72000 C:\Program Files\National Instruments\LabVIEW 2012\resource\mesa.dll
ModLoad: 0c7f0000 0c7f9000 C:\Program Files\National Instruments\LabVIEW 2012\resource\lvuste.dll
ModLoad: 35000000 3509b000 C:\Program Files\National Instruments\Shared\TDMS\tdms.dll
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ModLoad: 0e240000 0e2c7000 C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.6195_x-ww_44262b86\MSVCP80.dll
ModLoad: 0e2d0000 0e36b000 C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.6195_x-ww_44262b86\MSVCR80.dll
(1cb0.1a34): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=0e47f8b4 ebx=051f0040 ecx=051f0040 edx=061e5764 esi=22820840 edi=07b10040
eip=03c2050c esp=0e47f5cc ebp=0e47f810 iopl=0 nv up ei pl nz na po nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010202
*** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Program Files\National Instruments\LabVIEW 2012\resource\tdcore_12_0.dll -
tdcore_12_0!LvVariant:etContents+0xac:
03c2050c 837e3100 cmp dword ptr [esi+31h],0 ds:0023:22820871=????????
I cannot really tell whats going on. Looking for some pointers.
Regards,
Abel.

What is the problem with this event handler in LabView 8.0?

Please find attached a copy of a simple Event Structure VI. Can anyone please tell me why the Pos 0, Pos 1, Pos 2 work fine, but Pos 3 does Not????? It works in Version 7.1 of Labview, but Not in version 8.0. Any help here would be appreciate
Everything is Free! Until you have to pay for it.
Attachments:
ValChgEventBug.vi ‏29 KB

Hi,
It doesn't work because the logic is flawed. If you run the VI in Execution-Highlight mode you will see that for a value-change of, say, 7.0, all the cases (except the first one) are True! And since there is no data dependency, whatever case executes last will set the final position.
You will want to change the logic to check if the value falls in a range, rather than just being greater than something. For isntance, the psuedo-code would be:
"go to position 2 IF value >= 4 AND < 6"
You are missing the "AND" part. Hope this helps.
-Khalid

Tutorial on Event handling structure in labview

Hello,
can some one suggest a tutorial on event handling? I want to understand about the adavanced feature of the event handling structure like the dynamic even handling. Further is there any tutorial and examples using the user defined even handling function?
Regards
Gopal

Hi,
Thank you for those links. I would also like to know about the event menu in labview.Which has functions like create user event, register user events etc., further in event structure there is an option called show dynamic event terminal. what is its purpose and when and where should it be used?
Regards
Gopal

Labview slider event handling problems - revisited

This topic asked a question that was very close to a problem I am having:
Labview slider event handling problems
That is, how do I, using an event structure and/or other means, only read out the value of a slider control after the value change is finalized?
The extra constraint I'd like to place on this, which I believe will invalidate the answer given in the thread above, is that my slider control also has a digital display which can also be used to change the value without ever using the mouse. I cannot look for a value change followed by a mouse-up event if the mouse was not used to change the value.
Any ideas how this might be accomplished? FWIW, I am using LabVIEW 7.0

Each and every incremental value-change event generated by the movement of the slider is still detected and queued up for use by the event structure and the event structure loop wades through them all before it's done.
I have come up the attached "fix" (LV v7.0) for this problem. While it is not as clean a solution as I had hoped it would be, it's the best I can manage given what LabVIEW offers me to work with and it does work in the situation where I need to use it.
Now, within the Finalize Slider Events subVI, I'm keeping track of the most-recent values seen by the subVI, checking to see if they have changed, and reporting out that fact. That gives me a Changed/Not-Changed bit within the event case that I can use to control what code then gets executed. If the event case is just playing catch-up to the real value of the control, I can now see that fact and ignore it.
In this version I've also dumped the variant output and limited the VI to using DBL values. I decided it added complication to something that was too complicated already and I wanted the output terminals for other purposes anyway (reporting of the correct "OldVal" of the control).Message Edited by Warren Massey on 04-28-2005 03:56 AM
Attachments:
slider_events[5].llb ‏77 KB

Event Handler/Create User Event bug

This is a problem I've run into a few times on my system (Win2k) so I finally went back and reproduced it step by step since it wasn't too hard. It causes LabVIEW to crash and exit without saving.
- Create an Event Handler
- Place 'Register Events', wire output to dynamic event terminal
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- Place an Empty String Constant [""], wire to input of 'Create User Event'
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- Rename label from "Empty String Constant" to other such as "Event"
OR
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OR
- Place a boolean constant
- Set boolean property -> Visible Items > Label = True
- Name label something su
ch as "Event"
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- Place a constant of a different data type and wire it to the input of 'Create User Event'
LabVIEW immediately disappears (all changes are lost) and this error is displayed:
================================
LabVIEW.exe has generated errors and will be closed by
Windows. You wlil need to restart the program.
An error log is being created.
================================
If there is a more appropriate place to post things of this nature that don’t really add to the discussion group, but need to be brought to the attention of NI, please post a URL or submittal method. Thanks...

Thanks for the detailed request. We are aware of this exact issue, and the problem was actually fixed for LabVIEW 7.0 for Mac/Unix. Unfortunately, it did not get fixed for the initial release of LabVIEW 7.0 for Windows, but we have plans to include the fix in the first LabVIEW patch for 7.0.
Also, the Discussion Forum is great for notifications of this kind. For future reference, you also have the options of emailing NI engineers directly, or calling us with suspected bug fixes, if you would like more direct communication.
Thanks again, and have a great day!
Liz Fausak
Applications Engineer
National Instruments
www.ni.com/support

Event handler elements inside of the array

I have an array of clusters, of which inside the cluster are buttons. I want to be able to tie an event handler to these buttons ( they would all handle the event the same, the only difference would be the index they were handling)
A while back a similiar problem was posted here:
http://forums.ni.com/t5/LabVIEW/Array-of-Clusters-with-Graph-Y-Scale-Change-Event/td-p/1194181/page/...
However, this solution did not appear to be able to deliver the index of which button in the array was pressed .. this is critical for my application. The button is basically an "edit' buttonw which allows the user to edit the elements of the cluster through a popup. Obviously I need to know which cluster the user intends to edit.

nathand wrote:
One option: when the code starts, build an array of references to the edit buttons inside each cluster. Then, in the event case, search that array for the reference that triggered the event. The index at which the reference is found tells you which cluster to edit.
This might work, but it should be possible for the user to add/delete elements from the array so I would need to be able to do this even after program initialization.
Currently, I have just made dozen buttons alongside the array of clusters. But this workaround won't allow past a fixed number at program initialization.

Event handler eats up memory. Bad programing and/or bug.

Hello
I've been programming a GUI for a project. The basics of the program is a sample routine that updates a array once a second. Once the array is updated I use a event handler to plot the new array in a graph.
When I wrote this gui I think I've stumbled upon a bug in Labviews memory allocation.
If you have two loops. One that builds a array and then signals a loop with a eventhandler that reads the array and the event handler is stoped for a few seconds (by opening a sub vi or something inside the event handler), the memory goes berserk. When the event handler is free after the stop the memory is still allocated and does not return.
I could not find any information on this problem in the forum so I thought I would share this information with everyone. I managed to reproduce this phenomena in a small example (attached), if anyone is interested in it. The problem is simple to fix once you recognize the problem. However it was not the simplest problem to find (imho that is ).
Regards
Andreas Beckman
Attachments:
bug.zip ‏23 KB

Where are you seeing the memory being allocated? What tool are you using, task manager or LabVIEW profiling? I'm not seeing what you describe (LV 7.1.1 on a 3.4 GHz Pentium 4 w/ 1 Gb memory)
Thanks,
Putnam
Certified LabVIEW Developer
Senior Test Engineer
Currently using LV 6.1-LabVIEW 2012, RT8.5
LabVIEW Champion

Event handler switch creation (for repeated use )

Im creating a hyperterminal like application which reads from serial port and writes into serial port.
The reading and writing works almost fine..I also wants to create some custom "Key controls" that will send some prestored commands to the serial port.
I currently implemented two commands "ESC" and "FLASH " in the Key controls menu..
I want to send these commands ESC and FLASH each time i click a button in the menu.
I used event handler for it..and put the event handler inside an always running while loop.
But the problem is I can send only these commands only for one time during execution.
Repeated pressing of switches doesnt cause any effects..
Can somebody help please???
Im using labview 6.1. If u modify VIs using higher versions i cant open here..kindly include a jpg screenshot inthat case.
Thanking you.
Stephen.
Attachments:
Serial Port(stable release)1.2.vi ‏113 KB
Init.vi ‏32 KB
Write.vi ‏44 KB

Hi Stephen,
in LV7.1 your events will be executed whenever I press one of the according switches...
Notes:
-Don't make several event structures. Instead make one event structure with several event cases. Read the context help for the event structure!
-I would suggest to set the mechanical action of both switches to "latch when pressed" instead of "switch..." to give a feedback to the user as the switch will be reset after reading it...
-Generally be more styleguide-conform! Use right-click on terminals to create controls/constants to avoid coercion dots (spot the red colored dots in the image?). Make error in/out in the lower left/right of the connector pattern. Avoid block diagrams larger than the screen (or what kind of monitor do you use?).
Edited:
Sorry for weird display. I have to get used to the new image gallery feature of the forum (and will use "image to the left" only on rare conditions). Btw. the preview looks different to the actual post
Message Edited by GerdW on 05-28-2009 06:59 AM
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Programmatic change in multicolumn listbox value ignored by internal key event handler

The attached LabVIEW 8.5 vi demonstrates a problem I noticed using multicolumn listboxes. Upon changing the value (selected row) of the listbox programmatically, the very next press of the up or down arrow key behaves as if the value was never changed. For example, if the 3rd row is selected and then the listbox value is changed programmatically via a local variable or the value property to select the 0th row, pressing the down arrow key should now select the 1st row, but instead the 4th row is selected.
A workaround is to handle the Key Down? event myself as I've demonstrated in the attachment, but if this is a bug, I hope it can be corrected in a future release.
Larry
Attachments:
MC Listbox Bug.vi ‏30 KB

Hi Larry,
Pnt is correct and this is a known bug and relates to how the current row/ active row is handled when changing the values programmatically. Perhaps if you post your code we both can have a look and provide additional guidance.
Alternatively this forum post is related to your work around for using the event handler.
Regards,
Rishi L
National Instruments
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Use event handler programmatically

Hello, I use the Labview 8.2.1 and I would like to ask something about event handler.
I have some buttons and I use an event handler to perform their tasks. The buttons are used only with the mouse and not programmatically.
Now, I want to use a button programmatically without pressing it. I didn't find how to do this, so I created a boolean variable and I added to the event handler of a button a second "Event Specifier" of that boolean variable with the event "value change".
I assumed that it would work, but it does not, that is, the event handler is not used when the value of the boolean variable changes.
How can I solve it?
Thank you in advance.
Solved!
Go to Solution.

Write to the Value(Sgnl) property node of the variable you want to change. This will set off an event programatically.
- tbob
Inventor of the WORM Global

Migration from Serial polling to Serial queue with event handler

Hi, I am trying to migrate from classical serial polling communications to serial queue with "event handler" for the buttons pressed by the user. I have placed four while loops, one for the event handler, a second one for serial reading, a third one for serial writing (depending on what button was pressed) and the last one for processing what was read from the serial reading while loop, via a queue.
My attached device reads the signals from 8 sensor ( 4 temperature and another 4 temperature plus humidity in the same sensor ) and send them via serial to Lavbiew.
First of all, only once just after running the LV program, I must turn on my attached device with an ON command plus a carriage return after that the device will respond with the number of sensors plugged to it, disabling the corresponding buttons in the front panel. Then labview must wait until I pressed Acquire Button (event handler) and send a CF command plus what sensors to acquire plus a carriage return, then the device will respond continuously to labview with the sensor readings until I press the stop button (event handler), there is also another button to exit the program, also with event handler.
I am having problems using the event handler and the queues because I am new using these structures, I have looked at the LV examples but there is nothing concrete on using serial with event handler and queue.
Take a look at my VI and you will soon notice what kind of problems I am having, any suggestions will welcome.
Thank's in advance.
Regards.
Attachments:
serial queue.zip ‏76 KB

Hi Luisete,
Maybe the problem arise because you are En- and DeQueue in parallel. You do a lot of things in parallel, that is nice if you are sure that one loop doesn't have to wait for another loop. Make sure you don't dequeue before enqueue.
Hope this helps
I never knew that the standard error cluster output could be wired directly to the loop control of a while loop.
First time I see this

Event handling using CAN?

I am aware of how to make LabView respond to user interface events (keyboard presses, button presses, mouse moves, etc) and I'm also aware that the same event handling structure can be used to handle external (non-GUI) events- like those generated by a digital edge on a DAQmx input. My question is whether the same event handling structure can be used to handle external events coming in on a CAN network- via NI-CAN or otherwise?
Is there a good reference which summarizes ALL general types of events that can be handled in this way- not just the standard GUI events? I have a feeling that ActiveX and VISA are other ways to generate events, but can't find a good resource in general - or specifics on the NI-CAN side.
Thanks!
Nate

Thanks Mike- still not sure I understand. What should I wire to the Create User Event block in order for available events to show up in the dialog which allows me to configure events in a given frame? For example, I have an external micro-controller communicating with LabVIEW using a CAN network. Usually the communication is started by LabVIEW and sends commands out- but I also want to be able to handle asynchronous messages generated by this micro-controller in an event fashion without having do any polling. Is there some reference I can wire to the Create User Event block which will make an event like "Incoming CAN Network Traffic" available to be handled in an event structure?
Thanks again!

Mouse click on graph without event handling

Is there a way to detect mouse click on a graph without the event handling? My base version of LabVIEW does not have event handling features.
Thanks,
Ryan
Solved!
Go to Solution.

Leaving out the Event Structure seems like cruel and unusual punishment. My scorn is divided about 80/20 between NI for selling it and whoever tried to save a few bucks by buying it and then sticking it to you to workaround. Perhaps you are a student in which case you are free labor and it is all good.
Maybe your boss is a purist and dislikes Event Structures because they break the dataflow paradigm. The alternative is of course polling, and in this case you have plenty of data flowing! Unfortunately 99.9% of it is worthless. Here is a little example in LV8.2 (don't know your version) that uses polling to check on the mouse button. I only added a simple check for the button being pressed, if you want to know click (down/up) you can add a shift register and look for transitions in the button. I do check that the front panel is up front, otherwise it will still register clicks even though you may be surfing the web.
Hopefully everything is in the base package.
Attachments:
MouseClickNoEvent.vi ‏26 KB

Queue based UI Event Handler Pattern (CLD)

Hi, everybody:
I am trying to get a better understanding of the Queue based UI Event Handler pattern in CLD exam. So I made the attached small LabVIEW program in which 3 buttons(State 0, State 1, State 2) are the 'switches' of 3 LED lights (S0, S1, S2), respectively. After comparing with the Queue based UI Event Handler pattern in NI's slide, I got some questions at the following points:
(1) There are six items(Initialize, Waiting for Event, State 0, State 1, State 2 and Stop) in the Enum constant in my program. To make this program use standard Queue based UI Event Handler pattern, should I only use 3 cases(Initialize, Waiting for Event, Stop) in the case structure and put 4 events(State 0, State 1, State 2 and Stop) under the case of 'Waiting for Event' ? Is what I coded a standard Queue based UI Event Handler pattern?
(2) In the attached screenshot of Queue based UI Event Handler pattern in NI's slide, I found 'Start' is wired with 'Enqueue Element.vi'. Why is that? Should there be a 'Start' Case in the case structure?
(3) In my program, I wired 'Waiting for Event' with 'Enqueue Element.vi' in all events except 'Stop' event. Should I wire 'State 0', 'State 1', 'State 2' with 'Enqueue Element.vi' in their corresponding events, just like my second question in NI's slide?
BTW, I didn't find the exact Queue based UI Event Handler pattern in LabVIEW 2011, Should we code it by ourselves in the real CLD exam?
Thanks a lot in advance!
Chuan
Attachments:
Queue based UI Event Handler Practice.vi ‏18 KB
NI Slide.png ‏177 KB

Chuan wrote:
Hi, everybody:
I am trying to get a better understanding of the Queue based UI Event Handler pattern in CLD exam. So I made the attached small LabVIEW program in which 3 buttons(State 0, State 1, State 2) are the 'switches' of 3 LED lights (S0, S1, S2), respectively. After comparing with the Queue based UI Event Handler pattern in NI's slide, I got some questions at the following points:
(1) There are six items(Initialize, Waiting for Event, State 0, State 1, State 2 and Stop) in the Enum constant in my program. To make this program use standard Queue based UI Event Handler pattern, should I only use 3 cases(Initialize, Waiting for Event, Stop) in the case structure and put 4 events(State 0, State 1, State 2 and Stop) under the case of 'Waiting for Event' ? Is what I coded a standard Queue based UI Event Handler pattern?
What exactly are you trying to do with this program? Just using it to show a basic pattern for review?
Seems like you are trying to use Queues, a Case Structure, and Events all in one loop. Be careful not to try to be so advanced for this test. I still can't seem to figure out what the question you are trying ask is, but reply and we'll see if we can figure out an answer. You can put as many "states" in an Enum as you want but just not use them all during the program. I use fillers sometimes "just in case" I need to use it. Obviously, don't do this for a real program.
(2) In the attached screenshot of Queue based UI Event Handler pattern in NI's slide, I found 'Start' is wired with 'Enqueue Element.vi'. Why is that? Should there be a 'Start' Case in the case structure?
Your code is your code. This is just an example of the way that you could do it if you wanted to. You need to read the requirements document to determine exactly the way to Initialize and Start and whatever else your program. Typically, I've seen the following included in software using this structure: Initialize, Start, Run, Stop, Update Settings, Exit...and so on.
(3) In my program, I wired 'Waiting for Event' with 'Enqueue Element.vi' in all events except 'Stop' event. Should I wire 'State 0', 'State 1', 'State 2' with 'Enqueue Element.vi' in their corresponding events, just like my second question in NI's slide?
Well, you never ended up using the Initialize case. You need to Initialize outside the loop in your program. Again, try to explain your design more. It seems like what you have done is right, but I'm not sure what all you are trying to accomplish.
BTW, I didn't find the exact Queue based UI Event Handler pattern in LabVIEW 2011, Should we code it by ourselves in the real CLD exam?
All code on the CLD needs to be your own. Templates are just there as a starter for people who are not familiar with them. If you want to take the CLD, you should be at the point where you don't need the templates to do the work for you.
Thanks a lot in advance!
Chuan
See my responses above. Best of luck.
The pattern you have used in your program is *technically* fine, but in all the code I wrote for the CLD and in most of the examples I saw, everything was just a state machine with a enum driver. Be careful trying to violate the norm on this as you will likely run into more problems than solutions. You could also encapsulate your Queue into an FGV, which would modularize the code and look a little neater.
Nathan - Certified LabVIEW Developer

Canoe Event Handling in Labview

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