Problem with serial communication with xon/xoff controls

Hi

I am a newbie in C# and somehow have to develop a software that communicates with an external device that has a RS232 interface.

I have some experiences with RS232 programming but none of them involves handshacking.

The parameters of this device is as follows:

baudrate: 1200
parity: odd
data bits: 7
stop bits: 1
handshacking: Xon/Xoff

If I use the hyperterminal in windows, it responds ok. But I cannot get the C# program to work.

Here is the part of the settings in the program:

SerialPort BalancePort = new SerialPort();
BalancePort.PortName = 'COM1';
BalancePort.BaudRate = 1200;
BalancePort.DataBits = 7;
BalancePort.Parity = System.IO.Ports.Parity.Odd;
BalancePort.StopBits = System.IO.Ports.StopBits.One;
BalancePort.Handshake = System.IO.Ports.Handshake.XOnXOff;
BalancePort.ReadTimeout = 2000;

Here is the the write and read part:

BalancePort.Write(new byte[] { 0x1B, 0x50 }, 0, 2);
Thread.Sleep(5000);
string feedback = BalancePort.ReadExisting();

But it turns out every time it does not read a byte.

Any suggestions is highly appreciated.

ThanksP

Hi,
Sorry for the late reply only just found/saw your question!

If you are still interested here are some suggestions:

Try using an interrupt handler, in the form declaration (public Form1() ) put :

SerialBalancePort.DataRecieved +=SerialEventHandlerBalanceHandler(port_Balance);

and in the main program after the form declaration have

private void port_Balance(object sender,SerialDataReceivedEventArgs e)

{

InputData = SerialBalancePort.ReadExisting();

if (InputData != String.Empty)

{

this.BeginInvoke(new SetTextCallback(SetText), new object[]{ InputData});

}

private void SetText(string text)

{

this.rtbIncoming.Text += text;

}

As to why HyperTerm works and your code doesn't work you are send with the Write() command stopping the machine dead with the Thread.Sleep() and the trying to read the byte coming back with a non-blocking method when I think the data you are trying to read has come and gone.

Sorry you asked the question and no one got back to you sooner

Glenn

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Glenn Patton14y ago
Hi,
Sorry for the late reply only just found/saw your question!

If you are still interested here are some suggestions:

Try using an interrupt handler, in the form declaration (public Form1() ) put :

SerialBalancePort.DataRecieved +=SerialEventHandlerBalanceHandler(port_Balance);

and in the main program after the form declaration have
private void port_Balance(object sender,SerialDataReceivedEventArgs e)
{
InputData = SerialBalancePort.ReadExisting();
if (InputData != String.Empty)
{
this.BeginInvoke(new SetTextCallback(SetText), new object[]{ InputData});
}
}
private void SetText(string text)
{
this.rtbIncoming.Text += text;
}
As to why HyperTerm works and your code doesn't work you are send with the Write() command stopping the machine dead with the Thread.Sleep() and the trying to read the byte coming back with a non-blocking method when I think the data you are trying to read has come and gone.

Sorry you asked the question and no one got back to you sooner

Glenn