String Memory Management using Call Library Function

[rolfk]

Yes the boolean about "data includes array or string size" needs to be set to false. I forgot that as I could not run the code because of missing DLL.

And from looking at the Visual Studio solution file for your example program I do see that you target x64. So assuming you try to use the same DLL for LabVIEW, you must have LabVIEW 64 bit installed. And as I did mention in the post where I showed the possible solution, for 64 bit you have to make several extra changes, to make it work. You probably overlooked that or hadn't even realized you were actually running 64 bit LabVIEW.

[JustinB_Everix]

I have LabVIEW 64 bit installed but I use the 32 bit version exclusively. I am pretty certain I've been using the 32 bit DLL for the call library function. I'll try to make the changes you suggested and use the 64 bit DLL and corresponding LabVIEW version to see if that works.

[rolfk · Accepted solution]

This is a variant that "should" work for both 32 bit and 64 bit LabVIEW.

[wiebe@CARYA]

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@JustinB_Everix wrote:

I have LabVIEW 64 bit installed but I use the 32 bit version exclusively. I am pretty certain I've been using the 32 bit DLL for the call library function. I'll try to make the changes you suggested and use the 64 bit DLL and corresponding LabVIEW version to see if that works.

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If you get it wrong, it won't run. You'll get a broken arrow if you try to load a 32 bit dll in LV 64 bit, or vice versa. So, if the dll loads, it's the right one.

[JustinB_Everix]

So the changes you made are working, thank you for your help!

So it looks like you added extra bytes to each config value (IP/Port/Com Name) to ensure the total string sent have the expected amount of bytes for the compiler. 

I'd like to get better at interfacing with external programs, is there any literature you'd recommend? Obviously, I need to get a better understanding of the basics of compilers and DLLs.

[wiebe@CARYA]

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@JustinB_Everix wrote:

I'd like to get better at interfacing with external programs, is there any literature you'd recommend? Obviously, I need to get a better understanding of the basics of compilers and DLLs.

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I think you're beyond the level of the standard literature. This is hard stuff, you'll learn mostly by experience. IMHO.