.NET DAQmx dll x64 assembly will throw System.AccessViolationException when calling "DaqSystem.Local.GetPhysicalChannels"

[MendelBen]

I'm trying to develop a WPF application in .NET7 on VS2022 that uses DAQmx library.

I referenced -

• NationalInstruments.DAQmx.dll (Version 23.5.45.49381, the one that is under the directory 'Assemblies (64-bit)')
• NationalInstruments.Common.dll (Version 19.1.40)

Then, when the project's target platform is set to x64, the application crashes when it calls DaqSystem.Local.GetPhysicalChannels with a "System.AccessViolationException". This happen only when I run the program from the IDE. If I play the program straight from the "bin" folder, it runs nicely.

If I reference x86 version of DAQmx.dll and the project's target platform is set to x86, then the program runs both within the IDE and straight from the "bin" folder.

I want to keep developing the application with x64 target platform.

Any suggestions?

[astro12345]

I am having the same issue here also. Not able to target x64. Have you found a solution?

[AM7723]

I get that too, been trying to get around it for a couple of weeks, any update on that?

[rolfk · Accepted solution]

NI-DAQmx is NOT yet .Net Core compatible. It requires the .Net Framework 4 to run. If you want to run in .Net Core you will have to target the according C DLL directly through .Net Interop.

Here is a possible start for a C# Interop layer to DAQmx: https://github.com/jrdnwrth/NetDAQmx

And here is the NI-VISA variant: https://github.com/jrdnwrth/NetVisa

[MendelBen]

Thanks for the reply!
But here's the strange thing - even the ni-DAQmx example solutions (Which runs on .NET framework 4.5) behave in the exact same way.

[ZYOng]

Not sure if it has to do with the Visual Studio version. I am using Visual Studio Community 2015 and NI-DAQmx 2023 Q2. 

I can debug the shipping example without any issues. The default setting builds with 64-bit.

[MendelBen]

Hey Rolf, thanks for the answer.

Just note, I did use the example you presented from Github.

The same issue still persist when I configure VS to work on x64 platform. I.e., when I call any of the functions from the NI dll, a System.AccessViolationException is thrown.