Probing an Event Callback vi

Hi All.
Please could someone tell me why when I probe or enable tracing on the block diagram of an event callback vi nothing is indicated even after I know the vi was called because I can the the results of it being called. I am running Labview 2009.
Thanks in advance
Ian
Solved!
Go to Solution.

Hi and thanks for answering. Unfortunately I cannot post any code for security reasons. However the code I am degugging (not my code) is not using the usual event structure but uses a 'Register Event Callback' function to call a particular vi when a certain event (top level front panel control) is initiated. When I initiate the event I get the correct response on the top level vi (a user prompt pops up) so I know the vi is being called correctly. However if I pre-open the sub vi and set tracing or probes then initiate the event again I do not see anything register on tracing or in the probes (shown as not executed) even though the vi obviously ran again. The reason I want to probe the called sub vi is that a similar event is not working correctly and I was trying to see what happens with a functioning bit of code to draw comparisons. Hope I'm explaining this OK.
Thanks again
IanR

Similar Messages

Problem with register event callback in use of instrument control

now, i use the register event callback to register a value change of a boolean control on the front panel, and wire the cluster's ref of the instrument control parameters to the user parameter input, then create the callback vi. In the callback vi, i select the pump-control subvi, and pass the user parameter to the subvi. The problem is that, when i press the boolean control, the instrument (here is pump) can act, but immediately, the code crashes.
I use labview 8.6
Attachments:
callback vi.png ‏8 KB
register event callback.png ‏8 KB

You would wire the event registration wire that comes out of the Register for Events node into an event structure. You will need to right click on the event structure and check off "Show Dynamic Event Terminals" and it into that. Then you can create a new Event Case that uses the dynamic event. You can place your subVI in that event in whatever way you want. (Just drop the subVI in or do a Call by Reference there, or whatever.) Look in the Example Finder for "Dynamically Register for Events.vi".

How to place event callback components and "main-VI" components in the same Front Panel?

What I'm trying to accomplish:
Place a .NET component, which generates events, and other standard LabVIEW components in the same Front Panel. The standard LabVIEW components should be updated when events are being generated in the .NET component.
How I tried to solve it:
Problem:
The event callback code must reside in a separate event callback VI. In order to "pass the event up" to the main VI I tried to use a global variable. The interrupt does occur:
but I was hoping that the string indicator would be updated when the event occurred, but it wasn't.
Questions:
What's the best way to solve what I try to accomplish? If I want to solve the problem on the picture above, how would I do it (it may not be the best solution, but I'm still curious what's wrong)? Please feel free to be over-explicit when replying as I am novice LabVIEW programmer. Thanks in advance for any help.

There are two bundle functions for creating clusters. The function simply called Bundle operates almost exactly like the Build Array function I showed. The type of the output cluster depends on whatever you wire in as inputs. You don't have to supply a specific type parameter.
The function called Bundle by Name takes in a specific type of cluster in the top input and allows you to fill in the values of that specific type of cluster. To create the specific type of cluster you want, you need to create a cluster of string references. Here's how to do that:
Go to the Front panel and drop down an empty cluster shell.
Go to the Refnum palette and drop down a Generic Control Refnum. Now here's a cool trick to turn that generic refnum into a string-specific refnum (a so-called strictly-typed refnum). Grab a string from the controls palette and drag it into the Generic Control Refnum. Once you drop it, you'll see the refnum change its icon to display a string picture.
Make copies of this string refnum (as many as you need) and add it to the cluster shell.
Now, if you're making specific types of clusters to work with, now is the absolute best time to learn about typedefs if you haven't already. It will save you hours and hours (if not days) of development time in the future. Trust me!
Jarrod S.
National Instruments

Is there any event callback for "pre/post-register/unregister" object?

Dear all,
We noticed that there are rich set of event callback provided by TopLink, including "pre/post-Refresh/Build/Clone/Merge". However, we cannot found any callback method for "pre/post-register/unregister" events. They will be very useful, if we to manage the internal status of register/unregister to indicate whether it is still under the control of TopLink.
Thanks and regards,
William

William,
Those specific events do not exist. The postClone event is called after an object is registered. This is frequently used to copy non-persistent values from the cached original into the working copy.
There is also the ability to customize the clone/copy policy used by TopLink in creating the working copies in the UnitOfWork.
http://download-west.oracle.com/otn_hosted_doc/toplink/1013/DP4/_html/descfg028.htm#sthref3950
Doug

How to access new data in User Message Event Callback?

I am using the Simple LabVIEW OI as the model for my TestStand user interface.
The sequence sends a User Message to the OI to request the string array of tests to run.
But I am having great difficulty making this string array data available to the event callback VI.
I do not want to use a global variable and so my unsuccessful method so far has been as follows:
1. Use a Refnum to the Array and pass it into the Config Event Callbacks VI via the cluster
2. The "Selected Tests" in the input cluster in the Config Event Callbacks VI is a generic Control Refnum
3. This Selected Tests (at the bottom) is then bundled and passed into the User Parameter
4. But how do I convert the Selected Tests Control refnum back into the original string array in the actual callback?
Also if there is anyone that can suggest a better way of doing this then please let me know.
The bottom line is - how to get the latest data into the event callback function when it is called?
Many thanks,
Ronnie
TestStand 4.2.1, LabVIEW 2009, LabWindows/CVI 2009
Solved!
Go to Solution.

Hi Ray,
The 'Selected Tests' array refnum is #4 in the cluster order and matches all the way through - so I think that's OK.
In the final diagram above, I can get the Selected Tests cluster from the 'User Parameter', but it is still in the form of a refnum.
My problem is a lack of understanding in how to convert this 'Selected Tests' refnum back to the original data type (a string array).
Basically I want to get the string array from the 'Selected Tests' refnum.
As you can see from above I tried to use a property node. I've also tried to 'cast' the refnum to a 'more specific class' by choosing 'Array' but it's still ends up as a refnum.
I hope you see what I mean?
Thanks,
Ronnie
TestStand 4.2.1, LabVIEW 2009, LabWindows/CVI 2009

Active x and event callback in Labview

I have an active x written by Aanderaa Instruments (makes
weather and hydrology sensors), it contain various methods and events to get
the next line of records from a sensory scanning unit. The connection is
through the COM1, so far i have wired it up only using the methods to get next
record level, but then I have found that sometimes it does not get the complete
record from the COM port. So to solve that I have to use an event in the active
x to check for new record available. So what I want to do is send the event
(when complete record available) to VI that uses the get next record method to
pick up the data from the COM1 port and then send the data back to the main VI
for processing, plotting and writing.
My problem is that when I connect the output from the GetNextRecord method to a
indicator that I then wire on the connector pane to be an output from this
VI get an error that there is a wire function conflict. I have tried to
explain a bit better in the attached pdf file with diagrams.
The reason why I want to export the data back in the main VI is because it runs
continuously collecting data every 2 min and I plot them on a graph and write
them to a file so it will no work to have all that done in the event callback
VI that will only run ever 2 min, then it will reset the graph the whole time
and I want continuous data plotting for 10 days of historic data records. I
also have a few other sensors that come in through a connector board that are
written o the same file.
hope somebody can give me some hints
Attachments:
labview question.pdf ‏721 KB

Duplicate post, click here for the original: http://forums.ni.com/ni/board/message?board.id=170&message.id=135639#M135639
LabVIEW Champion . Do more with less code and in less time .

Event callback with active x in labview

I have an active x written by Aanderaa Instruments (makes
weather and hydrology sensors), it contain various methods and events to get
the next line of records from a sensory scanning unit. The connection is
through the COM1, so far i have wired it up only using the methods to get next
record level, but then I have found that sometimes it does not get the complete
record from the COM port. So to solve that I have to use an event in the active
x to check for new record available. So what I want to do is send the event
(when complete record available) to VI that uses the get next record method to
pick up the data from the COM1 port and then send the data back to the main VI
for processing, plotting and writing.
My problem is that when I connect the output from the GetNextRecord method to a
indicator that I then wire on the connector pane to be an output from this
VI get an error that there is a wire function conflict. I have tried to
explain a bit better in the attached pdf file with diagrams.
The reason why I want to export the data back in the main VI is because it runs
continuously collecting data every 2 min and I plot them on a graph and write
them to a file so it will no work to have all that done in the event callback
VI that will only run ever 2 min, then it will reset the graph the whole time
and I want continuous data plotting for 10 days of historic data records. I
also have a few other sensors that come in through a connector board that are
written o the same file.
hope somebody can give me some hints
Attachments:
labview question.pdf ‏721 KB

Hello!
I checked the PDF file with snippets of your code and it looks alright, no issues or comments regarding that from my side. However it is really difficult for us to troubleshoot when we don’t have the ActiveX control available and even though we had access to the control it would still be quite tricky to find the cause of the problems you are experiencing since we don’t have the hardware and so on.
I found one link only that mentioned wire conflicts when talking about COM objects and ActiveX and you can find it here:
http://digital.ni.com/public.nsf/websearch/0CED780C5D5EDCD5862569D9005AE1FA?OpenDocument
Regards,
Jimmie A.
Applications Engineer, National Instruments
Regards,
Jimmie Adolph
Systems Engineer Manager, National Instruments Northern Region
Bring Me The Horizon - Sempiternal

Photoshop crash on mac in 'slct' event callback

Hi,
I am getting consistent Photoshop crash on mac (12.0.4) when handling 'slct' event callback in my extension
The crash itself produce the same repor (see bellow) t as described here: http://forums.adobe.com/message/3473893#3473893
I narrowed it down to the case when you have 2 or more documents in "consolidate all to tabs" mode and you try to pull out one of them.
If you have a callback registered like this for 'slct' ExternalInterface.addCallback("PhotoshopCallback" + CSXSInterface.instance.getExtensionId(), eventCallback) and you try to access Photoshop.app.activeDocument Photoshop crashes with the bellow report
It's hapening onlyon mac.
Do you have any advice how to workaround it or even better a fix?
Regards
Lukas
Process: Adobe Photoshop CS5 [2734] Path: /Applications/Adobe Photoshop CS5/Adobe Photoshop CS5.app/Contents/MacOS/Adobe Photoshop CS5 Identifier: com.adobe.Photoshop Version: 12.0.4 (12.0.4x20110407.r.1265) (12.0.4) Code Type: X86-64 (Native) Parent Process: Adobe Flash Builder 4.5 [1259] Date/Time: 2012-04-03 17:57:37.438 +0200 OS Version: Mac OS X 10.6.8 (10K549) Report Version: 6 Interval Since Last Report: -2676258 sec Crashes Since Last Report: 36 Per-App Interval Since Last Report: -1577868 sec Per-App Crashes Since Last Report: 36 Anonymous UUID: 3253FFFA-8C14-41BE-B83D-82BE373CCD9F Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000000 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 com.adobe.owl 0x000000010371d186 OWLDockGetAnchor + 8186 1 com.adobe.owl 0x0000000103683bc2 0x103652000 + 203714 2 com.adobe.owl 0x000000010368acb6 OWLHandleNSApplicationEvent + 40 3 com.adobe.Photoshop 0x000000010024e831 0x100000000 + 2418737 4 com.adobe.Photoshop 0x0000000100278615 0x100000000 + 2590229 5 com.adobe.PSAutomate 0x0000000121ccfbcf CPsWActionControl::Get(CPsWActionReference const&, CPsWActionDescriptor&) + 31 6 com.adobe.PSAutomate 0x0000000121cac44b CPsDocuments::DocumentCount() + 85 7 com.adobe.PSAutomate 0x0000000121c93b3f CPsApplication::GetActiveDocument(MultiScript::InterfacePtr&) const + 77 8 com.adobe.PSAutomate 0x0000000121c47ffe CPsApplication::HostGet(int, ScCore::Variant&) const + 2606 9 com.adobe.PSAutomate 0x0000000121ce72d8 MultiScript::TProxyBase::get(int, ScCore::Variant&, ScCore::Error*) const + 240 10 com.adobe.AdobeScCore 0x00000001221d72e2 ScCore::LiveObject::get(ScCore::String const&, ScCore::Variant&, ScCore::Error*) + 242 11 com.adobe.AdobeScCore 0x000000012222c4a1 _getProperty(APEDOMObjectRef*, ScCore::Variant const&, ScCore::Variant&, ScCore::Error&) + 113 12 com.adobe.AdobeScCore 0x000000012222dad7 APEObjectGetPropertyCB(Opaque_APEPlayer*, void*, void*, APEOpaqueAtom*) + 263 13 com.adobe.adobeswfl 0x0000000122932cf3 APXGetHostAPI + 21603 14 com.adobe.adobeswfl 0x0000000122fa4914 SWFLPlayer_Initialize + 2208548 15 ??? 0x000000012ab64e0e 0 + 5011557902 16 ??? 0x000000012ab652ec 0 + 5011559148 17 ??? 0x000000012abc2883 0 + 5011941507 18 com.adobe.adobeswfl 0x0000000122fa2915 SWFLPlayer_Initialize + 2200357 19 com.adobe.adobeswfl 0x0000000122f85d6d SWFLPlayer_Initialize + 2082685 20 com.adobe.adobeswfl 0x0000000122fa4914 SWFLPlayer_Initialize + 2208548 21 ??? 0x00000001267cb5e3 0 + 4940674531 22 ??? 0x00000001267cbc43 0 + 4940676163 23 ??? 0x000000012a04b807 0 + 4999919623 24 com.adobe.adobeswfl 0x0000000122a273b7 APXGetHostAPI + 1022759 25 com.adobe.adobeswfl 0x0000000122a28a83 APXGetHostAPI + 1028595 26 com.adobe.adobeswfl 0x0000000122d317dc APXGetHostAPI + 4210508 27 com.adobe.adobeswfl 0x0000000122d91276 SWFLPlayer_Initialize + 31878 28 com.adobe.ape 0x00000001207c7946 APEInitialize + 1398

Sure, I know about PSEvenScrubber. This on is different beast though. When activeDocument is null it's just it and you get an exception in the script if you try to use it, but in this case code like this:
var ho:HostObject=app.activeDocument.hostObjectDelegate or
var d:int=Photoshop.app.documents.length;
cause the crash of the whole Photoshop
Keep in mind that if i just switch between the documents without pulling them out of the dock everything works fine.
But it can be releated though as it seems that something is not initialized properly, but in this case on deeper level than actionScript

Event Callback Problems during compilation

Hi
I try to register a callback vi with the "Register Event Callback"-node. I
pass a reference of an array as user parameter into to the "Register Event
Callback"-node. Everything works well in the development environment. But
when I try to build an executable I get the Error "1003 . The vi is not
executable".
What is wrong?
Mareike

Hello Mareike,
you can surch in the http://www.ni.com/support/ for "error" and "1003". There you will find a lot of links where this error is discussed. With a little luck, there will be an answer.
Regards ThomasD

Event Callback from a Reentrant VI Recursion Error

Greetings,
I am using Register Event Callback with an ActiveX object to respond to user mouse events. The problem is that when I run the VI (the main, calling vi) as reentrant, Labview gives an error that the "Callback.vi" is attempting to recursively call "Main.vi".
Is there a way around this problem? I intend to run two copies of "Main.vi", so reentrant execution seems necessary.
- Colin Holbrook

Hi Colin,
Are you placing the Register Event Callback inside of the Main VI and then wiring the same Main VI to the VI Reference terminal? If so, then that explains why you are getting an error. You cannot use the Register Event Callback to call a VI within itself. If this is not the case, then please post a simple VI that demonstrates the problem.

Recursive ActiveX register event callback VI

Hi!
I am trying to control a motor in LV2013 using the ActiveX concept. When I use a "register event callback VI" function, can I call the same VI that calls a VI (with the "stop rule" controlled be the user data terminal, of course, inside)? By default, callback Vis that one can create for this are all reentrant (preallocated clone) and synchronious (according to help). However, both when I use the "server VI reference" ("This VI") and when I create a reference and browse for the same file - "register event callback" shows me a broken wire.

_Basil_ wrote:
As far as I understood, putting a movement method in the loop will not give any result, so I tought in the direction of the recursive callback. However, I found this post. Would you in general agree that the callback VI cannot be recursive? I attach my code in LV13 (if you need me to convert, I will)
Sorry, I'm still on LabVIEW 2012 here, so can't look at your VIs. I don't understand your comments in these sentences though. What do you mean by putting a movement method in a loop will not give any result? And why would you ever want a recursive callback? The callback is called each time the event occurs. There's no sense in making it recursive, nor would you want to re-register for a callback on an event inside a callback VI. Normally a callback should contain very little logic; it should primarily pass some piece of information (through a queue, user event, etc) back to the main thread and let the main logic handle it.

Configure Event Callbacks in test stand using labview

Hi,
I was going through Full OI - Configure Event Callbacks.vi in the test stand example. Can you please explain me how the vi works and what is techniwue behind it?
When i open the individual VI's in the reference, I could see more that 1 control in the front panel. But Only the user parameter is wired in the vi? Why is it so?
Regards
Gopal

Hi Gopal,
When the TestStand Engine fires events, this VI specifies how your Operator Interface will respond. For example, let's examine the first event callback registered in Full OI - Configure Event Callbacks.vi , Exit Application. When the TestStand Engine receives the message to shutdown, and then finishes its neccessary shutdown procedures, it will send a message to the Operator Interface. For the Operator Interface to receive this message, it must "listen" for it. In LabVIEW, this is done by Registering an Event Callback. See the links below for details on how to implement this.
The answer to your specific question is in step 7 of the first link below. When TestStand sends the message to LabVIEW, there is information that is always passed. The other input controls contain this information. To create a VI that always includes these controls, right-click on the VI Ref input to the Reg Event Callback Property Node, and then select Create Callback VI.
Here are two references that talk about handling ActiveX callbacks in LabVIEW in general:
Registering and Handling .NET and ActiveX Events
Register Event Callback (Not in Base Package)
Cheers,
David Goldberg
National Instruments
Software R&D

Executable and Register event callbacks

Hi,
I have been running into an issue regarding the building of an executable that has register event callbacks (specifically Test Stand Callbacks). The VI that is responsible for setting up the event registration is an asynchronous VI. During development everything works but during deployment of an executable the Callback is either not running or capturing the event from the Test Stand engine (I am looking for the end of execution event). The setup is not reporting an error, and the pathing to the callback VIs is correct. Any Ideas on this?
Does the Teststand engine not post a endexecution callback when running from a executable labview environment?
Thanks,
Andrew

akonecki wrote:
Hi,
I have been running into an issue regarding the building of an executable that has register event callbacks (specifically Test Stand Callbacks). The VI that is responsible for setting up the event registration is an asynchronous VI. During development everything works but during deployment of an executable the Callback is either not running or capturing the event from the Test Stand engine (I am looking for the end of execution event). The setup is not reporting an error, and the pathing to the callback VIs is correct. Any Ideas on this?
Does the Teststand engine not post a endexecution callback when running from a executable labview environment?
Thanks,
Andrew
The TestStand engine is singular regardless of what is hosting the components so it will post the appropriate callbacks. Try some tracing and see what flags up in your callback VI.

Event Callback VI with LVOOP / overhead, caveats, future

OK another exploratory post from me. To anyone who has put up with this kind of thing from yours truly many times in the past, apologies. Completely impervious to any objections, here goes:
I have discovered a new toy : Registering event callback VIs. OK, I have used them before but a previous post by James McNally about his MVC framework revealed to me a usage which I had not previously thought of. Thanks for that James.
I like LVOOP. One pattern which is quite easy to understand is the command pattern in conjunction with state machines where we essentially replace the individual states of a state machine with external VIs. This makes it far easier to customise behaviour and allows for re-use of the core state machine for differing functionalities. Cool.
We can leverage this with LVOOP by passing different "commands" to the state machine depending on the real object being utilised and thus we have a nice extensible architecture. Again, cool. If we need to change one common action, we simply update that VI and instantaneously all ancestors share the new code in that command object. Double cool.
Problem is that I love User Events. The idea of having an extensible object model gets awkward to handle when you start using Events to handle communications in and out of the object. Create a Parent, Implement the 15 Events required. Create a child, Implement the 15 Parent events and the 12 new events. Create a Grandchild, Implement the 15 Grandparent, the 12 Parent and then the 25 new Events. Armageddon occurs when you want to change the common functionality for the sixth Event of the Parent. Now you need to go to each and every ancestor which uses them and update them. Wait a second, isn't LVOOP supposed to save me from this kind of crud? Frustration ensures. Can you ever be sure you got all instances? What about those obejcts not listed in the project, maybe you forgot one of them...... Nasty testing and debugging ensues.
I think I may have (partially) found the answer. What we need to do is basically do the same thing we have done with the command pattern and extract the individual frames of the event structure and place them into external VIs so that we can 1) re-use the VIs in each level of hierarchy and 2) maintain all the other niceties of Events.
Turns out that using Callback VIs for each level of the object hierarchy can help to solve this problem. You need to have a method with a different name for each level of the hierarchy which exposes the events int his way because each method will most likely have different input values.
Has anyone else done things like this? Are there limitations as to what can and can't be done with this arrangement? Any nasty bugbears waiting for me around the corner? How to deal with events which should give some kind of return value? Do I encorporate the return value into an implementation-agnostic return channel (again Events of course) with the object in question providing one return user event for each callback function which requires a return value?
Say hello to my little friend.
RFC 2323 FHE-Compliant

Grr, I was trying to attach a file (whose contents apparently didn't match the file name?!!) when I ran out of time to edit and now I lost my text.
Here's an example.
Base class swaps out a control Caption for Label upon "Mouse Enter"
Child class swaps out a control Label for Caption on "Mouse Leave"
Grandchild increments a counter (stored in Description) for every "Mouse Enter"
Trivial but get's at what I mean.
I know I can do this in other ways but
1) I don't need a parallel process
2) I'm just having fun
Darn, I can't attach a zip. Rename this file to .zip and unpack. Sorry guys.
Say hello to my little friend.
RFC 2323 FHE-Compliant
Attachments:
LVOOP with Event callbacks.txt ‏78 KB

Event callback timing

When I am using dynamic events and transmit a counter as event data each time I fire the event, I can have multiple consumers that receive the identical count. Thus, only a single event is generated each time and signaled to all consumers. Ok, so far.
Now, I am using the Register Event Callback function in LV8.2. to fire events from an ActiveX component (pressing buttons on a joystick device) and use a dynamic event to signal this to multiple consumers. Again, I add a counter to the dynamic event data. What happens now is that the consumers receive different counts, even if I only click the joystick button once. As if there are multiple events generated. For 2 consumers, 2 events are being generated, for 3 consumer 3 events and so on. But how would the callback VI know that there are multiple consumers?
I tried reentrant and non-reentrant callback VIs and see no difference ("reentrant" is specified in Help, but I do not fully understand why that should be needed).
Could anyone explain this behaviour to me? Thank you!
Dirk

Hi Daniel,
thank you for your reply. Although I managed to include the ActiveX components supplied with my special input device, I am not in general familiar with ActiveX. Therefore, I have no idea how to find something as general as "keyboard hit". However, triggered by your reply I now tried it with a modified version of LV's example file using Excel worksheets. There, I do not see the described behaviour.
Well, I will check again on that special device driver now. At the moment, it is not working at all, which looks fishy...
Dirk

Probing an Event Callback vi

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