Thread th = new Thread(ReceiveRun);
                th.Start();


        // Цикл извлечения сообщений,
        // запускается в отдельном потоке.
        void ReceiveRun()
        {
            while (true)
            {
                try
                {
                    string s = null;
                    while (ns.DataAvailable == true)
                    {
                        //// Определение необходимого размера буфера приема.
                        //byte[] buffer = new byte[_tcpСlient.Available];

                        ns.Read(inBuffer, 0, inBuffer.Length);
                        s += Encoding.Default.GetString(inBuffer);
                    }

                    if (s != null)
                    {
                        ShowReceiveMessage(s);
                        s = String.Empty;
                    }


                    // Вынужденная строчка для экономия ресурсов процессора.
                    // Неизящный способ.
                    Thread.Sleep(100);
                }
                catch
                {
                    ErrorSound();
                }

                if (_stopNetwork == true) break;

            }
        }

       // Код доступа к свойствам объектов главной формы  из других потоков
        delegate void UpdateReceiveDisplayDelegate(string message);
        void ShowReceiveMessage(string message)
        {
            if (chart1.InvokeRequired == true)
            {
                UpdateReceiveDisplayDelegate rdd = new UpdateReceiveDisplayDelegate(ShowReceiveMessage);

                // Данный метод вызывается в дочернем потоке,
                // ищет основной поток и выполняет делегат указанный в качестве параметра
                // в главном потоке, безопасно обновляя интерфейс формы.
                Invoke(rdd, new object[] { message });
                chart1.Series[0].Points.Clear();
                chart1.Series[1].Points.Clear();
                chart1.Series[2].Points.Clear();
                chart1.Series[3].Points.Clear();
                chart1.Series["1,3 мкм"].Points.AddY(inBuffer[1] << 8 + inBuffer[0]);
                chart1.Series["2,11 мкм"].Points.AddY(inBuffer[3] << 8 + inBuffer[2]);
                chart1.Series["1,8 мкм"].Points.AddY(inBuffer[5] << 8 + inBuffer[4]);
                chart1.Series["1,93 мкм"].Points.AddY(inBuffer[7] << 8 + inBuffer[6]);
            }
            else
            {
                // Если не требуется вызывать метод Invoke, обратимся напрямую к элементу формы.
                chart1.Series[0].Points.Clear();
                chart1.Series[1].Points.Clear();
                chart1.Series[2].Points.Clear();
                chart1.Series[3].Points.Clear();
                chart1.Series["1,3 мкм"].Points.AddY(inBuffer[1] << 8 + inBuffer[0]);
                chart1.Series["2,11 мкм"].Points.AddY(inBuffer[3] << 8 + inBuffer[2]);
                chart1.Series["1,8 мкм"].Points.AddY(inBuffer[5] << 8 + inBuffer[4]);
                chart1.Series["1,93 мкм"].Points.AddY(inBuffer[7] << 8 + inBuffer[6]);
            }


        }

        private void button2_Click(object sender, EventArgs e)
        {
            tcpСlient.Close();
            tcpStream.Close();
            tcpСlient = new TcpClient();
        }

  if (s != null)
{
запись в лог s
ShowReceiveMessage(s);
        s = String.Empty;
}

                            byte[] bytes = new byte[tcpСlient.ReceiveBufferSize];
// Заказываете буфер для чтения неизвестно какого размера -
//  то, что вернет tcpСlient.ReceiveBufferSize тут и то, что он вернет 3мя строками позже не обязательно совпадают

                            while (tcpStream.DataAvailable == true)
// Если данные есть - читаем их, если нет - то не читаем, а выдаем пустой buffer
// (returndata во 2й раз будет не null, а String.Empty)
                            {
                                tcpStream.Read(bytes, 0, (int)tcpСlient.ReceiveBufferSize);
                                returndata = Encoding.UTF8.GetString(bytes);
// Это зачем ???
                                count++;
                            }
                            if (returndata != null)
// Это просто жесть :)
                            {
                                Invoke(rdd, new object[] { bytes });
                                str = returndata;
                                returndata = String.Empty;
                            }

        private void ReceiveRun()
        {
            
            UpdateReceiveDisplayDelegate rdd = new UpdateReceiveDisplayDelegate(Display);
            try
            {
                while (true)
                {
                        if (tcpStream.CanRead)
                        {
                            byte[] bytes = new byte[256];
                            while (tcpStream.DataAvailable == true)
                            {
                                tcpStream.Read(bytes, 0, (int)256);
                                count++;
                            }
                            Invoke(rdd, new object[] { bytes });
                         }
                        else
                        {
                            label1.Text = "Прием невозможен";
                            th.Abort();
                            tcpСlient.Close();
                            tcpStream.Close();
                            return;
                        }
                 }
            }
            catch
            {
                label1.Text = "ошибка";
            }
        }

        delegate void UpdateReceiveDisplayDelegate(Byte [] mydata);
        private void Display(Byte[] mydata) //вывод на форму
        {
            Int32 temp;
            temp = ((mydata[3] << 24) + (mydata[2] << 16) + (mydata[1] << 8) + mydata[0]);
            label1.Text = temp.ToString("D");
            label3.Text = Convert.ToString(count);
                //if (mydata[0] > 0) label2.Text = "OK";
                //else label2.Text = "0";
        }

byte[] bytes = new byte[256];
...

int size = 0;
while(size<256)
{
  while (tcpStream.DataAvailable == true)
   {
     size+=tcpStream.Read(bytes, size, 256-size);
   }
  if (size<256) Thread::Sleep(100);
}
count++;

Invoke(rdd, new object[] { bytes });

if(count_old != count)Invoke(rdd, new object[] { bytes });

       private void button3_Click(object sender, EventArgs e)//Отправить
        {

            if (tcpStream.CanWrite)
            {
                outBuffer[0] = 1;
                if (checkBox1.Checked)
                {
                    outBuffer[1] = 2;
                    outBuffer[2] = 1;
                }
                else
                {
                    outBuffer[1] = 2;
                    outBuffer[2] = 0;
                }
  
                tcpStream.Write(outBuffer, 0, outBuffer.Length);
            }
            else
            {
                label1.Text = "Передача невозможна";
                th.Abort();
                tcpСlient.Close();
                tcpStream.Close();
                return;
            }
        }