Serial port Data after scanning

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I am working in windows application. I am using serial COM port in my application. I am getting previous data from serial port after second scan . First time scan I got the data, second time I am recieving the same data.My code in datarecievehandler event of serial port

public static void DataReceivedHandler1(object sender, SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
 
string indata = sp.ReadLine();
 
//sp.DiscardInBuffer();
//sp.DiscardOutBuffer();
 
}

indata gets same as previous data .I tried to use discardbuffer but its not helping...
If you guys have any solutions , then please let me know

Posted 30-May-14 1:12am

RAHUL(10217975)

Updated 30-May-14 1:16am

Abhishek Pant

v2

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Herman<T>.Instance 30-May-14 7:17am

did you close and reopen the sp port after ReadLine()?

RAHUL(10217975) 30-May-14 7:24am

No, I am opening serial port in form load and closing in window close

2 solutions

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User 59241 · Answer 1 · 2014-05-30T02:37:00

This is a robust approach:

C#

private SerialPort _serialPort;
    _serialPort = new SerialPort();
    _serialPort.Open();
    _serialPort.DataReceived += dataReceivedHandler;

        private void dataReceivedHandler(object sender, SerialDataReceivedEventArgs args)
        {
            if (!_serialPort.IsOpen)
                return;

            int BytesToRead = _serialPort.BytesToRead;

            byte[] data = new byte[BytesToRead];

            int NumBytes = _serialPort.Read(data, 0, BytesToRead);

            String mystring = Encoding.ASCII.GetString(data, 0, NumBytes);
        }

Herman<T>.Instance · Answer 2 · 2014-05-30T01:44:00

Solution 1

Use

sp.ReadExisting();

in that case you read the complete buffer in stead of 1 line

Posted 30-May-14 1:44am

Herman<T>.Instance

Updated 30-May-14 2:03am

v2