FoxAPI:

void change(ParamBlk FAR *parm)
{
#define p0 (parm->p[ 0 ].val) 

    Value val;
   int   status;
// Для примера запишем  9  байт
   char * szBuf=malloc( 10 );  
   memmove(szBuf, "123456789 ", 10 );

 _MemFill(&objct, 0 ,sizeof(Value));
   objct = p0;

  if (objct.ev_type == 'O')
 {
_MemFill(&val, 0 ,sizeof(Value));
val.ev_type = 'C';
val.ev_length  = strlen(szBuf);
val.ev_handle = _AllocHand(val.ev_length);
_HLock(val.ev_handle);
_MemMove((char *) _HandToPtr(val.ev_handle ),szBuf,val.ev_length);
_HUnLock(val.ev_handle);

  if (!(status= _SetObjectProperty(&objct,  "MyProperty" , &val,  0 ))) _RetInt( 1 , 10 );
else  _RetInt( 0 , 10 );

}

= change(thisform)

	Value  objеct;
	BOOL ExitAllThread = FALSE;

void DataWaitingAsync(void* pParams)
{
 char szBuf[ 254 ];
 Value val;

 while (!ExitAllThread)
{

// Тут прочитали в szBuf(не важно как и что, но что там гарантированно 
//лежит то что надо проверено и сомнений не вызывает)

if (objct.ev_type == 'O')
 {
_MemFill(&val, 0 ,sizeof(Value));
val.ev_type = 'C';
val.ev_length  = strlen(szBuf);
val.ev_handle = _AllocHand(val.ev_length);
_HLock(val.ev_handle);
_MemMove((char *) _HandToPtr(val.ev_handle ),szBuf,val.ev_length);
_HUnLock(val.ev_handle);

  if (!(status= _SetObjectProperty(&object,  "MyProperty" , &val,  0 ))) 
 _Execute( "oApp.MyEvent('OK')\0 ");
else  _Execute( "oApp.MyEvent('BAD')\0 ");
}
}
ExitThread( 0 );
}

void InitPort(ParamBlk FAR *parm)
{
#define p0 (parm->p[ 0 ].val)  
unsigned long uThrID;	
HANDLE hThr;

_MemFill(&objеct, 0 ,sizeof(Value));
objеct = p0;

hThr=CreateThread(NULL, 0 ,(LPTHREAD_START_ROUTINE)DataWaitingAsync,NULL, 0 ,&uThrID);
}

 = InitPort(thisform)