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DLL Pointer Arguments Input and Output

Hi There,

 

I am working on interfacing a USB device through a vendor supplied DLL. I was able to use the Shared DLL Import Wizard to get VIs set up for the exposed DLL functions. Many of the functions have pointers as function arguments, and I am confused as to why the VI shows both an input and an output for the pointer argument. I am not sure how to wire up the in/out node for the pointer argument to get what I need.

 

I am attaching a picture for reference as well.

 

I have a simple function prototype - SI_STATUS WINAPI SI_Open(DWORD dwDevice, HANDLE* cyHandle);

 

I am looking to receive a return value from the function as well as data from the pointer I am passing. When the Import Wizard VI is created, there is a parameter "cyHandle" input and a "cyHandle out" output created on the VI block diagram. (I noticed a similar type of setup in examples I found for Call Library Function Node). So to get my handle, do I need to hook up controls/indicators to just one or both? It is not clear to me how this is supposed to work.

 

Thank you.

 

Brian

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it looks to me the output is the same as the input (a duplicate)

The reference of the handle is probably passed through the dll.

 

Just wire the input...  

LabVIEW style programming : Inputs on the left, outputs on the right

Kind regards,

- Bjorn -

Have fun using LabVIEW... and if you like my answer, please pay me back in Kudo's 😉
LabVIEW 5.1 - LabVIEW 2012
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