datacap.cs

using System;
using System.Threading.Tasks;
using System.Text;

namespace datacap_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            int port = 9001;
            var deviceID = "<device serial number 24 char>";

            System.Net.Sockets.UdpClient udpClient = new System.Net.Sockets.UdpClient();
            System.Net.IPEndPoint groupEP = new System.Net.IPEndPoint(System.Net.IPAddress.Any, port);

            // Bind
            udpClient.Client.Bind(groupEP);

            // Listen 
            var listener = Task.Run(() =>
            {
                while (true)
                {
                    byte[] recvBuffer = udpClient.Receive(ref groupEP);
                    var resp = Encoding.UTF8.GetString(recvBuffer);
                    if (resp.Contains(deviceID + " is at:"))
                        Console.WriteLine("Found DC Direct at: " + resp.Substring(resp.IndexOf(':') + 1));
                }
            });

            // Broadcast
            var data = Encoding.UTF8.GetBytes("Who has " + deviceID);
            udpClient.Send(data, data.Length, "255.255.255.255", port);

            listener.Wait(5000);   // wait 5 seconds for response
            Console.ReadLine();
        }
    }
}