My application program was working until I got a new NI USB interface.

[LJGremillion]

I installed a new NI USB interface with the 4.0 Communications Manager. My application software gets to a piece of code that executes :

currentVFD.CLOSE()

currentVFD.OPEN()

I then get a "AccessViolationException". This has been working fine until now.

I am also using VB 2010 if that matters. Any ideas?

[Vince Shen]

AccessViolationException error indicates that the program tries to access invalid memory.

NI-FBUS 4.0 is released before Visual Studio 2010. To ensure the compatibility, could you try the earlier version of VB, such as 2008?