串口高波特率丢失字符

void DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    try
    {
        if (!serialPort.IsOpen)
        {
            return;
        }        

        Byte[] receivedData = new Byte[serialPort.BytesToRead];        //创建接收字节数组
        serialPort.Read(receivedData, 0, receivedData.Length);         //读取数据

        serialPort.DiscardInBuffer();
        serialPort.DiscardOutBuffer();

        string read = Encoding.ASCII.GetString(receivedData);

        read = read.Replace("\0", "");        
    }
    catch (Exception ex)
    {        
    }  
}

void DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    try
    {
        if (!serialPort.IsOpen)
        {
            return;
        }

        int n = serialPort.BytesToRead;
        byte[] buf = new byte[n];
        int readLength = 0;
        int offset = 0;
        while (offset < n)
        {
            readLength = serialPort.Read(buf, 0, n - offset);
            if (readLength < 0)
            {
                return;
            }
            offset = offset + readLength;
        }

　　　　 string read = Encoding.ASCII.GetString(buf);          
    }
    catch (Exception ex)
    {        
    }   
}