收到无人接听时C＃UDP通信结束连接

Question

我正在编写简单的应用程序，以便通过UDP与arduinos进行动态通信。

我在C＃pc app中编写UDP类时遇到了困难。

我没有收到客户回答后结束功能有问题。如果我与正在启用的客户端连接，没有问题，应用程序在收到答案后运行良好且流畅。

STRING_operations str = new STRING_operations();

    static int communicationPort = 8888;
    string[] arduinoPool = new string[64];

    private void populateArduinoPool()
    {
        for (int i = 0; i < 25; i++)
        {
            arduinoPool[i] = "192.168.1." + Convert.ToString(170 + i);
        }
    }

    private string mainCommunication(string vIPAdsress, string Message)
    {
        string answer = string.Empty;
        int port = communicationPort;

        Console.WriteLine("IP address: " + vIPAdsress);
        Console.WriteLine("Message to sent: " + Message);

        Byte[] sendBytes = Encoding.ASCII.GetBytes(str.sendString(Message));
        Byte[] receiveBytes = null;

        var IP = IPAddress.Parse(vIPAdsress);
        var udpClient = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        udpClient.ReceiveTimeout = 1000;
        udpClient.SendTimeout = 1000;
        var sendEndPoint = new IPEndPoint(IP, port);
        var receiveEndPoint = new IPEndPoint(IP, port);
        var clientReturn = new UdpClient(port);

            udpClient.SendTo(sendBytes, sendEndPoint);
            Console.WriteLine("Message sent");
            try { 
            receiveBytes = clientReturn.Receive(ref receiveEndPoint);
            Console.WriteLine("Message is being receiving");

            if (receiveBytes == null || receiveBytes.Length == 0)
            {
                Console.WriteLine("No answer");
                ;
            }

                Console.WriteLine(Encoding.ASCII.GetString(receiveBytes));
                answer = str.trimString(Encoding.ASCII.GetString(receiveBytes));
                Console.WriteLine("Trimed answer: " + answer);

            udpClient.Disconnect(true);
            return answer; }
        catch (Exception e)
        {
            Console.WriteLine(e);
            return e.ToString();
        }
    }

    public void populateComboBox(ComboBox CB1)
    {
        Console.WriteLine("Populating arduino pool");
        populateArduinoPool();
        string message = str.sendString("HELLO");

        for (int i = 0; i < 25; i++)
        {
            Console.WriteLine("Trying to communicate with: " + arduinoPool[i]);
            if (mainCommunication(arduinoPool[i], message) == "YO")
            {
                Console.WriteLine("Established");
                CB1.Items.Add(arduinoPool[i]);
            }
        }
    }

    public bool checkIfActive(ComboBox CB1)
    {
        string message = str.sendString("HELLO"); ;
        if (mainCommunication(CB1.SelectedText.ToString(), message) == "YO")
            return true;
        else
            return false;
    }