C++/CLI callback to C#

Question

I have a C library (DLL) where I have callback functions with defined datatypes.

Now I am writing Wrapper(DLL) for this in C++/CLI. This Wrapper Dll will be used in my C# application.

How to Implement the callback in C++/CLI so that i can write the call back function in C# an passt it through the wrapper to the C librarby.

Dll Libray ...

# C libary (DLL) *.h file
...
typedef void (*TOnMonitoringStateCB)(const ROBOT_STATE);
typedef void (*TOnMonitoringDataCB)(const LPMONITORING_DATA);
...
DRFL_API void _SetOnMonitoringState(LPROBOTCONTROL pCtrl, TOnMonitoringStateCB pCallbackFunc);
DRFL_API void _SetOnMonitoringData(LPROBOTCONTROL pCtrl, TOnMonitoringDataCB pCallbackFunc); 
...
class CDRFL
{
public:
    // robot status data
    void SetOnMonitoringState(TOnMonitoringStateCB pCallbackFunc) { _SetOnMonitoringState(_rbtCtrl, pCallbackFunc); };
    // robot operating data
    void SetOnMonitoringData(TOnMonitoringDataCB pCallbackFunc) { _SetOnMonitoringData(_rbtCtrl, pCallbackFunc); };
...

Wrapper (DLL) C++/CLI ...

# C++/CLI *.h (my try)
...
public delegate void ManagedTOnMonitoringStateCB(const RobotState);
public delegate void ManagedTOnMonitoringDataCB(const LpMonitoringDate);
...
public ref class WrapperClass
{
   ...
   void SetOnMonitoringState(ManagedTOnMonitoringStateCB^ callbackFunc);
   void SetOnMonitoringData(ManagedTOnMonitoringDataCB^ callbackFunc);
   ...
}
# *.cpp (my try)
...
void WrapperClass::SetOnMonitoringState(ManagedTOnMonitoringStateCB^ callbackFunc)
{
    IntPtr cbPtr = System::Runtime::InteropServices::Marshal::GetFunctionPointerForDelegate(callbackFunc);
    _rbtCtrl->SetOnMonitoringState(static_cast<CLibrarbyc::TOnMonitoringStateCB>(cbPtr.ToPointer()));
};
void WrapperClass::SetOnMonitoringData(ManagedTOnMonitoringDataCB^ callbackFunc)
{
    IntPtr cbPtr = System::Runtime::InteropServices::Marshal::GetFunctionPointerForDelegate(callbackFunc);
    _rbtCtrl->SetOnMonitoringData(static_cast<CLibrarbyc::TOnMonitoringDataCB>(cbPtr.ToPointer()));
};
...

C# ...

...
_rbtCtrl.SetOnMonitoringState(OnMonitoringState());

 void OnMonitoringState()
 {
     textBox1.AppendText("...");
 }

_rbtCtrl.SetOnMonitoringData(OnMonitoringData());

 void OnMonitoringData()
 {
     textBox1.AppendText("...");
 }
...

The C++/CLI seems to be OK, but in the C# part I always have problems with the Converting the types. It also can be a problem of the initialisaten of the callbackfunction and the handling of the function in C#. But maybe there is also and erro in the C++/CLI Wrapper or it can be done easier, but it compiles.