HINSTANCE hLib;
cfunc1 Init_MODULES;
cfunc2 Close_MODULES;
cfunc4 MODULESTransfer;
cfunc5 GetMODULESDeviceName;
char mod[150];
int i;

UCHAR inBuffer[16];
READ_BUFFER* pinBuffer;
WRITE_BUFFER outBuffer;

boolean load_DLL() {
  BOOLEAN dll_ok;

  hLib = LoadLibrary("ITRA_APCOMM.dll");
  if (hLib != NULL) {
    dll_ok = TRUE;
    if (GetModuleFileName((HMODULE)hLib, (LPTSTR)mod, 150) == 0) dll_ok = FALSE;
    Init_MODULES = (cfunc1)GetProcAddress((HMODULE)hLib,"Init_MODULES");
    Close_MODULES = (cfunc2)GetProcAddress((HMODULE)hLib,"Close_MODULES");
    MODULESTransfer = (cfunc4)GetProcAddress((HMODULE)hLib,"MODULESTransfer");
    Get_MODULESDeviceName = (cfunc5)GetProcAddress((HMODULE)hLib,"Get_MODULESDeviceName");
    } else {
      dll_ok = FALSE;
    }
    if (Init_MODULES == NULL) dll_ok = FALSE;
    if (Close_MODULES == NULL) dll_ok = FALSE;
    if (MODULESTransfer == NULL) dll_ok = FALSE;
    if (Get_MODULESDeviceName == NULL) dll_ok = FALSE;
    return dll_ok;
  }

...
  if (load_DLL() == TRUE) {                          // check the DLL
    if ((Init_MODULES(0) & 0xFF00) == 0x2200) {      // check the usb driver
...
        
      // Code request and LED output
      // fill the writeBuffer with LED vars
      outBuffer[0] = ....;
...
      pinBuffer=MODULESTransfer(&outBuffer);

      if (pinBuffer->TransferResult == TRUE) {
        for (i=0;i<16;i++) {
          inBuffer[i]=pinBuffer->ReadBuffer[i];
        }
        // process the key events in inBuffer[3], inBuffer[4]

      } else {
        // Transfer Error
      }

      // the Module can be leaved open for loops, but close it on program end
      Close_MODULES();
    } else {
      // Error Init
    }
  }