How sending data separately

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C#

hi guys
it`s question about , sending data separately , im send one integer as info form my sensor to server program , i want to send another integer as another sensor to server but there is problem how separate them from each other , and how i can understand which on that i get it in my server program :
client program : Void send

<pre lang="cs">
void sendata(int d)
        {
            byte[] data = new byte[1024];
            data  = BitConverter.GetBytes(d);
            sock.Send(data, data.Length, SocketFlags.None);
        }

then i call this void in this timer and send data to server :

<pre lang="cs">
private void timer1_Tick(object sender, EventArgs e)
        {
            try
            {
                sendata(a);
            }
            catch
            {
                //MessageBox.Show("error","er");
                //sock.Shutdown(SocketShutdown.Both);
                //sock.Close();
                //Close();
            }
        }

and use this code in server :

        private void timer1_Tick(object sender, EventArgs e)
        {
            DateTime startTime = DateTime.Now;
            byte[] data = new byte[1024];
            int recv = client.Receive(data);
            int size = BitConverter.ToInt32(data, 0);
            if (recv != 0)
            {
                label3.Text = " ";
                label3.Text = "co2 ppm is : " + size;
                // label4.Text=""+ siz;
            }
            progressBar1.Maximum = 100;
            progressBar1.Minimum = 0;
            progressBar1.Value = size;
            label2.Text = DateTime.Now.Subtract(startTime).TotalMilliseconds.ToString() + "         :Time To Action" + " ms ";
        }
please tell me how i can send two or more data (int) and get and separate them in server ...