Call function in LabView from a DLL, then access global variable from DLL

Question

I have created a DLL in LabWindows with a function and a structure.  I want to call the function from within LabView and then access the global structure.  I am able to call the function from the DLL with a "Call Library Function Node" and can access the return value, but I cannot figure out how to access the global structure.  The structure is declared in the DLL header file with __declspec(dllimport) struct parameters.
Is there any way of accessing this structure without using the Network Variable Library?
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Answer 1

dblok wrote:
When you say "access to" or "the address of" the global variable, do you mean to pass the variable as an argument to the function call in the DLL?  If so, then I was not really sure how to pass a cluster from LabView by using the "Call Library Function Node".
Yes, that's exactly right.  I would include a pair of helper functions in the DLL to read and write the global variable.  Alternatively you might write separate helper functions for each field inside the global structure, depending on the number of fields and whether you want to do any validation on the values.
You can pass a cluster by reference to a function that expects a struct by setting the parameter to Adapt to Type, so long as the cluster does not contain any variable-length elements (strings or arrays).  The cluster needs to match the struct exactly, and sometimes that involves adding extra padding bytes to make the alignment work.  Variable-length elements in LabVIEW need to be converted to clusters containing the same number of elements as the struct definition (for example, if your struct contains char name[12], you would create a cluster of 8 U8 values, and you could use String to Array of Bytes followed by Array to Cluster to convert a LabVIEW string into that format).  If the struct contains pointers it gets more complicated, and it may be easier to write functions in the DLL to access those specific elements individually.
If you can't get this working or need help, post your code and an explanation of the error or problem you're seeing.
EDIT: it is also possible to include a single function in the DLL that returns the address of the global variable, which LabVIEW can then use to access and modify the data, but that's more complicated and likely to lead to crashes if you don't get the memory addressing exactly right.