Strange data when reading from usb serial port

Question

I am trying to read data from a serialport. When i use USB adapters i get junk instead of what is sendt.

What i expect (And get with a normal serialport)

 0001 C0  23:33:41.9114 00
 0001 C1  23:34:17.8207 00
 0001 RT  00:00:35.90   00
n0002
 0002 C0  23:34:32.8372 00
 0002 C1  23:42:36.2617 00
 0002 RT  00:08:03.42   00
n0003
 0003 C0  23:42:44.3947 00

What i get when connected through a USB serial port (0x00 0x3F ...)

003F003F783F003F003F003F003F003F
003F003F003F003F003F3F3F3F003F00
3F3F78003F003F003F003F003F780000
3F003F783F003F003F003F003F003F00
3F003F003F003F003F3F3F3F003F003F
3F78003F003F00

Also when i use Putty to connect it displays correct texte even through USB serial port.

What can be wrong here? How does Putty "fix" the corrupt data.

Edit: Added code used for reading

    SerialPort p = new SerialPort(Conf.Value("ExternalClockPort"), int.Parse(Conf.Value("ExternalClockBaud")), Parity.None, 8, StopBits.Two);
p.Handshake = Handshake.RequestToSend;
p.Open();
byte[] buffer = new byte[512];
String command = "";
while (!Done)
{
    int cnt = p.Read(buffer, 0, buffer.Length);
    File.AppendAllText(this.appDataDirectory + "ExternalClock.log", ASCIIEncoding.ASCII.GetString(buffer, 0, cnt));
    command = ExternalClock.parseCommand(command + ASCIIEncoding.ASCII.GetString(buffer, 0, cnt));
}

Please show the code that you use to read from the serial port. Do you use ReadLine with some encoding set? — Tomislav Markovski
Added reading code. I use ASCII encoding. The problem is that it behaves differently with different serialports. — klundby
Looks like you are using the wrong baudrate / serial port settings. — Jan

Tomislav Markovski Tomislav Markovski · Accepted Answer · 2011-12-28T10:38:23

OK, so you need to register an event DataRecieved and read the port data from it. Also, make sure your port initialization values are correct.

_sp = new SerialPort(Conf.Value("ExternalClockPort"), int.Parse(Conf.Value("ExternalClockBaud")), Parity.None, 8, StopBits.Two);
_sp.DataReceived += new SerialDataReceivedEventHandler(Port_DataReceived);
_sp.Open();


private void Port_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    int totalBytes = _sp.BytesToRead;
    byte[] buffer = new byte[totalBytes];
    _sp.Read(buffer, 0, totalBytes);
}

Strange data when reading from usb serial port

2 Answers