Connect to pressure sensor using c# to get the value ,doesn't work in c#

Question

I have a sensor ,i connect to this sensor using network cable.I should send a command to this sensor to get the value .

The sensor ip is :192.168.2.44
my computer ip:192.168.2.111

I used a program called hercules as you can see here to connect to the sensor :

In the TCP server tab i define the port to 3000 when i clicked on listen button the program shows this (as you can see in the picture) client connected

After connecting i can send a command to the sensor to get the value as you can see in the picture:

I found this code but it does't work and i can't send a command by this to get the value ,the main problem is my code can't connect to the port could you give me some help . i am so new in socket programming .

Code:

try
{
    string hostname = "192.168.2.44";
    int portno = 3000;
    IPAddress ipa = Dns.GetHostAddresses(hostname)[0];
    try
    {
        System.Net.Sockets.Socket sock = new System.Net.Sockets.Socket(System.Net.Sockets.AddressFamily.InterNetwork, System.Net.Sockets.SocketType.Stream, System.Net.Sockets.ProtocolType.Tcp);
        sock.Connect(ipa, portno);
        if (sock.Connected == true)  // Port is in use and connection is successful
            Console.WriteLine("Port is Closed");
        sock.Close();
    }
    catch (System.Net.Sockets.SocketException ex)
    {
        if (ex.ErrorCode == 10061)  // Port is unused and could not establish connection 
            Console.WriteLine("Port is open");
        else
            Console.WriteLine(ex.ErrorCode);
    }
}
catch (Exception e)
{
    Console.WriteLine(e.ToString());
    Console.ReadLine();
}

Exception:

A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 192.168.2.44:3000

I should implement something like the hercules using c#

Answer 1

In your screenshots, PC is a master device (it opens a listening server socket), and the sensor is a slave. While your code assumes, that PC tries to connect to a sensor as a client.

The minimal code snippet is this:

        var listener = new TcpListener(IPAddress.Any, 3000);
        listener.Start();

        using (var client = listener.AcceptTcpClient())
        using (var stream = client.GetStream())
        {
            // build a request to send to sensor
            var request = new byte[] { /*...*/ };
            stream.Write(request, 0, request.Length);
            // read a response from sensor;
            // note, that respose colud be broken into several parts;
            // you should determine, when reading is complete, according to the protocol for the sensor
            while (!/* response is complete */)
            {                    
                // stream.Read calls here
            }
        }

Also note, that if the protocol is textual, then you could build request and parse response using StreamWriter/StreamReader.