C2DModules

device.cs

using Microsoft.Azure.Devices.Client;
using System;
using System.IO;
using System.Threading.Tasks;

namespace c2d_device
{
    class Program
    {
        static async Task Main(string[] args)
        {
            const string cs = "HostName=.azure-devices.net;DeviceId=;ModuleId=;SharedAccessKey=";
            ModuleClient client = ModuleClient.CreateFromConnectionString(cs, TransportType.Mqtt);
            await client.SetMessageHandlerAsync((Message message, object ctx) => 
            {
                Console.WriteLine(new StreamReader(message.BodyStream).ReadToEnd());
                return Task.FromResult(MessageResponse.Completed);
            }
            , null);
            Console.WriteLine("Listening");
            Console.ReadLine();
        }
    }
}

service.cs

using Microsoft.Azure.Devices;
using System;
using System.Text;
using System.Threading.Tasks;

namespace c2d_service
{
    class Program
    {
        static async Task Main(string[] args)
        {
            var cs = "HostName=.azure-devices.net;SharedAccessKeyName=iothubowner;SharedAccessKey="
            var service = ServiceClient.CreateFromConnectionString(cs);
            var msgText = "Msg from: " + DateTime.Now.ToLongTimeString();
            var msg = new Message(Encoding.UTF8.GetBytes(msgText));
            await service.SendAsync("", "", msg);
            Console.WriteLine("Msg Sent: " + msgText);

        }
    }
}