Solution
To control the volume of your PC you will need to use a
Call Library Function Node to call the dll's that you will need in LabVIEW. The dll file that you will need to access is the user32.dll this can be found in your computer under Windows >> System32 >> user32.dll. The VI that you will need to create will match that of the picture below. Please note that the constants going into Node B and Node C are configured as Hexadecimal.
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The Call Library Function Nodes above should be configured as follows:
Node A Functions Tab
- Library name or path contains user32.dll
- Function name is set to FindWindowA
- Thread is set to Run in UI thread
- Calling convention is set to stdcall (WINAPI)
Node A Parameters Tab Prototypes should include the 3 following elements
- hWnd - Type is set to Numeric, Data type is set to Unsigned 32-bit Integer, and Pass is set to Value
- lpszClassName - Type is set to Numeric, Data type is set to Signed 32-bit Integer, and Pass is set to Value
- lpszWindowName - Type is set to String, the Constant box is checked, String format is set to C String Pointer, Minimum size is set to <None>
Node B and Node C Functions Tab
- Library name or path contains user32.dll
- Function name is set to SendMessageA
- Thread is set to Run in UI thread
- Calling convention is set to stdcall (WINAPI)
Node B and Node C Parameters Tab Prototypes should include the 5 following elements
- LRESULT - Type is set to Numeric, Data type is set to Signed 32-bit Integer
- hWnd - Type is set to Numeric, Data type is set to Unsigned 32-bit Integer, and Pass is set to Value
- Msg - Type is set to Numeric, Data type is set to Unsigned 32-bit Integer, and Pass is set to Value
- wParam - Type is set to Numeric, Data type is set to Unsigned 32-bit Integer, and Pass is set to Value
- Iparam - Type is set to Numeric, Data type is set to Unsigned 32-bit Integer, and Pass is set to Value