LabVIEW
Labview silent crash when closing vi calling dll
Solved!
Hi Efri,
@Efrihauge wrote:
I'm calling a third party DLL from labview, and this works perfekt, only thing is when i close the vi using the DLL, the complete labview eviroment makes a silent crash
Apparently "this works NOT perfect" when your VI/IDE/EXE crashes.
Are you sure you are calling that 3rd party DLL correctly?
Hi Efri,
@Efrihauge wrote:
Yes I'm sure, I have now tried to call the dll from a C++ compiler, and the same issue is there, when the program exit, it got an exception.
Is there any way to make a workaround, I mean it looks drastic that labview terminate because of an exception from a dll call.
Is there any way to handle this from labview. ?
I don't think so, but I'm not an expert with DLLs. Wait for RolfK to chime in…
Why does it "look drastic" when an EXE crashes upon errors in DLL calls? You should rather avoid those exceptions at all, independently from the caller environment!
Either there is a bug in the DLL or you call it with wrong parameters: what does the creator of that DLL say about this problem?
If LabVIEW simply crashes there is a very serious bug either in the configuration/implementation of the Call Library Node or in the DLL itself. It means that the DLL somehow destroyed memory or tried to access memory that is not valid. After such a grave violation there simply is no safe way to continue and Windows simply terminates the process. Even if there was a way to prevent Windows from doing that, it would only lead from bad to worse whatever you try to do after that. Basically the integrity of your process was violated and continuing after that would almost certainly just destroy even more and lead nowhere useful.
If your developer confirms that there is a problem in the DLL, you will have to wait for him to fix it or tell you how to avoid it. Avoiding it almost certainly will consist of not calling the offending API or at least only with parameters that don't trigger the bug. But that is something that developer needs to be able to tell you, nobody else can as we don't know the DLL in question and certainly not the internal details about it!
If the error is really only happening at DLL unload, one possible workaround is to prevent the DLL from unloading. However that comes with other possible problems such as having to restart LabVIEW altogether anyhow as soon as you want to change, move, rename or delete the DLL on disk. A loaded DLL causes Windows to lock its file and any attempt to change that file in any way is blocked. The easist way to prevent the DLL from unloading is to keep somewhere in your LabVIEW a VI open that contains a Call Library Node referencing that DLL. Don't ever close that VI or the top level VI that calls this VI. This way the Call Library Node will keep the DLL loaded!
@Efrihauge wrote:
Hi GerdW
The creator know there is an error when the dll is unloaded it throw an execption.
But he haven't time yet to solve it and just ask me to make a workaround.
But there seems not to be any way to handle theese kind of errors in labview, right?
Br
Esben
If the creator doesn't have time to fix such an egregious bug, then you probably don't have time to use it. That's like buying a car from a dealer, complaining that you can't stop the engine unless you disconnect the alternator and the battery, and the dealer telling you he doesn't have time to fix it; find a way to work around it, instead.
Maybe you should tell his boss that he doesn't have time to fix a bug that renders his dll unusable.
