Mitsubishi RM-501

I dont know any good Solutions for this old Robot.

Yes, it is as you said, windows is difficult with this.
Use Serial Port and check the high, low's manualy after sending over TXD and RXD.
Dont use overlapped. Use the windows API commands for checking the serial port bits, no Portio.dll etc.
I have done it and it works ... for stall use and extra routine which count after getting no low.
Parallel is not working.

sample code i can give u in c++, delphi
has not worked either.

Or use Linux with java:

page 96 with samples: (sorry german)
http://www.aicas.com/papers/Diplomarbeit-Kubo.pdf

bool MyDlg::SendCommand(int command, int wert1, int wert2, int wert3, int wert4, int wert5)
{
bool ok=true;
CString Wert1,Wert2,Wert3,Wert4,Wert5;
Wert1.Format("%d",wert1);
Wert2.Format("%d",wert2);
Wert3.Format("%d",wert3);
CString sendstring;
CHAR* ccb;
CHAR* fccb;
//Nest
if (command == 1){fccb="N";ccb="T\r";}
//Move
if (command == 2){fccb="M";sendstring="O "+Wert1+"\r";ccb=sendstring.GetBuffer();}
//GripPressure
if (command == 3){fccb="G";sendstring="P "+Wert1+","+Wert2+","+Wert3+"\r";ccb=sendstring.GetBuffer();}
//GripClose
if (command == 4){fccb="G";ccb="O\r";}
//GripOpen
if (command == 5){fccb="G";ccb="C\r";}
//Speed
if (command == 6)
{
fccb="S";
sendstring="P "+Wert1+"\r";
ccb=sendstring.GetBuffer();
m_speed.SetPos(wert1);
}
//Reset
if (command == 20){fccb="R";ccb="S\r";}
//Senden über Com Port
int timeout=robotimeout;
if (command < 7 command==20)
{
DWORD reward;
int lang=strlen(ccb);
bWriteRC = WriteFile(m_hCom, fccb,1,&iBytesWritten,NULL);
Sleep(200);
bool fertig=false;
while(fertig==false)
{
GetCommModemStatus(m_hCom,&reward);
if (reward & MS_CTS_ON)
{
fertig=true;
}
Sleep(1);
timeout--;
if (timeout < 0){AfxMessageBox("Timeout bei der Kommunikation mit dem Roboter",0,NULL);ok=false;break;}
}
bWriteRC = WriteFile(m_hCom, ccb,lang,&iBytesWritten,NULL);
}

return ok;
}

please make m_hCom your create handle of your used comport.
Also use the Comport Settings like I described here for my software.
Notice the 200ms after FIRST byte !!
it is very stable, we run about a half year with that.

SW1: 1,2,4,5,6,7,8=Off 3=On
SW2: 1,3,4,8=Off 2,5,6,7=On

perhaps u can translate the API in Delphi ? don't know ...