Question

Possible Duplicate:
C# serialport and hyperterminal

Problem

I’m having trouble with my serial connection. I can send data to my device, but I can’t read data. If I use Hyperterm, everyting work fine – I see the data coming in and going out.

Using my code, however, my serial port object never receives any data, but data I send is received by the device.

Any ideas?

Project Info:

• WPF
• .NET 3.5 (not the Client Profile version)
• Developing on Windows 7
• Visual Studio 2010
• DA-15 serial to USB

Hyperterm settings:

• COM20
• Bits per second: 115200
• Data bits: 8
• Parity: None
• Stop bits: 1
• Flow control: None

C# Code:

SerialPort serial = new SerialPort();

serial.PortName = "COM20";
serial.BaudRate = 115200;
serial.DataBits = 8;
serial.Parity = Parity.None;
serial.StopBits = StopBits.One;
serial.Handshake = Handshake.None;

serial.Open();
serial.Write("Hello World\r\n");    // Echoed on device screen

while (0 == serial.BytesToRead)     // Never receive a response
    System.Threading.Thread.Sleep(100);

char[] first = new char[serial.BytesToRead];
serial.Read(first, 0, first.Length);

Edit:

I noted it above, but just to make sure everyone knows, I am using a USB to Serial Port cable. I don’t think this is the issue because it works on Hyperterm, but just in case.

Answer 1

Take a look at the MSDN Example they are using a seperate thread to check for Data. You can also subscribe to the DataReceived Event to see if it is firing at all. And there is a Community comment about setting DTR and RTS to true, if the connected device needs them it will not transmit data.