Rs232

[kubusse]

Hallo,
ich versuche ein Byte auf die RS232 Schnittstelle auszugeben,
funktioniert aber nicht, was mache ich falsch?
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//INITIALISIEREN DER RS232 MIT BUTTOMCLICK//
void __fastcall TTIMERTICK::Button3Click(TObject *Sender)
{
chandle = CreateFile ("COM1",GENERIC_READ | GENERIC_WRITE,0,NULL,OPEN_EXISTING,0,NULL);

if (chandle == INVALID_HANDLE_VALUE)
{
Application->MessageBox("RS232 IS INT","RS232",MB_OK | MB_ICONINFORMATION);
}
else
{
wsprintf(error,"RS232 INIT ERROR WITH %d ERRORS", GetLastError());
Application->MessageBox(error,"RS232",MB_OK | MB_ICONINFORMATION);
}
dcb.BaudRate = CBR_57600; // set the baud rate
dcb.ByteSize = 8; // data size, xmit, and rcv
dcb.Parity = NOPARITY; // no parity bit
dcb.StopBits = ONESTOPBIT; // one stop bit
SetCommState(chandle, &dcb);
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//RS232 SENDEN MIT BUTTOMCLICK//
//---------------------------------------------------------------------------
void __fastcall TTIMERTICK::Button2Click(TObject *Sender)
{
x = 0;
WriteFile(chandle,&x,1,0,0);
Application->MessageBox("WRITE TO RS232","RS232",MB_OK | MB_ICONINFORMATION);
}