How can I send hex-code via TCP in C# language

I'm new to C# programming and I'm trying to write TCP client that will send hex code to the server via hex code read some metadata from server side.I managed to connect with the server but could not send hex code.Could you please look what I'm missing here.

using System;
using System.IO;
using System.Text;
using System.Net.Sockets;


public class clnt
{

public static void Main()
{

    try
    {
        TcpClient tcpclnt = new TcpClient();
        Console.WriteLine("Connecting...");

        tcpclnt.Connect("192.168.80.128", 557);
        // use the ip address as in the server program

        Console.WriteLine("Connected!");
        Console.WriteLine("Sending Hex Code...");


        string str = Console.ReadLine();
        Stream stm = tcpclnt.GetStream();


        ASCIIEncoding asen = new ASCIIEncoding();
        byte[] ba = asen.GetBytes(str);
        var data = new byte[] { 0xCF, 0xC4 };
        Console.WriteLine("Transmitting");

        stm.Write(ba, 0, ba.Length);

        byte[] bb = new byte[100];
        int k = stm.Read(bb, 0, 100);

        for (int i = 0; i < k; i++)
            Console.Write(Convert.ToChar(bb[i]));

        tcpclnt.Close();
    }

    catch (Exception e)
    {
        Console.WriteLine("Opps " + e.StackTrace);
    }
}

}


//C++ code
int main()
{
    client.Initialize("192.168.80.128", 557);

    std::this_thread::sleep_for(std::chrono::seconds(2));

    std::string xid = U8("NASA_Arnold_AFB_Airshow");

    std::vector<std::uint8_t> command = {0xCF, 0xC4};

    command.push_back(static_cast<std::uint8_t>(xid.length()));

    command.insert(command.end(), xid.begin(), xid.end());

    std::cout << command.size() << std::endl;

    client.Correspond(command, 10);

    std::this_thread::sleep_for(std::chrono::seconds(3));

    command.clear();

    command = {0xC8, 0xC3};

    std::cout << client.Response().size() << std::endl;

    std::vector<std::uint8_t> idhandle(client.Response().begin() + 2, client.Response().end());

    command.insert(command.end(), idhandle.begin(), idhandle.end());

    client.Correspond(command, 3);

    std::this_thread::sleep_for(std::chrono::seconds(3));

    for(auto element : client.Response())
        std::cout << static_cast<int>(element) << std::endl;

    std::uint8_t size = client.Response().back();

    std::cout << "size of xid:" << static_cast<int>(size) << std::endl;

    client.ReadN(size);

    std::this_thread::sleep_for(std::chrono::seconds(3));

    std::cout << std::string(client.Response().begin(), client.Response().end()) << std::endl;

    command.clear();

    command = {0xC8, 0x4A};

    command.insert(command.end(), idhandle.begin(), idhandle.end());

    std::cout << idhandle.size() << std::endl;

    for(auto element : idhandle)
        std::cout << static_cast<int>(element) << std::endl;

    client.Correspond(command, 97);

    std::this_thread::sleep_for(std::chrono::seconds(3));


    std::cout << std::string(client.Response().begin(), client.Response().end()) << std::endl;


    std::getchar();

    return 0;
}