class Program
    {
        static void Main(string[] args)
        {
            Func<ushort[], int, int, byte[]> getNBytesAt = (arr, idx, n) => arr
                .Skip(idx)
                .Select(BitConverter.GetBytes)
                .Aggregate<IEnumerable<byte>>(Enumerable.Concat)
                .Take(n)
                .ToArray();

            var epoch0 = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

            using (var master = ModbusIpMaster.CreateIp(new TcpClient("10.1.6.10", 502)))
            using (var writer = new BinaryWriter(File.OpenWrite(@"E:\testdata\clock.raw")))
            {
                var plcData = master.ReadHoldingRegisters(1, 0, 4);
                DateTime dtInit = DateTime.Now;
                var curTimeInit = BitConverter.ToUInt32(getNBytesAt(plcData, 0, 4), 0);
                var timeInit = BitConverter.ToUInt32(getNBytesAt(plcData, 2, 4), 0);
                var pc2Init = GetNetworkTime();
                while (true)
                {
                    var now = DateTime.Now;
                    plcData = master.ReadHoldingRegisters(1, 0, 4);
                    foreach (var us in plcData)
                    {
                        writer.Write(us);
                    }
                    writer.Write(now.ToBinary());
                    Console.Clear();

                    var curTime = BitConverter.ToUInt32(getNBytesAt(plcData, 0, 4), 0);
                    var time = BitConverter.ToUInt32(getNBytesAt(plcData, 2, 4), 0);
                    Console.WriteLine(writer.BaseStream.Position + " bytes written");
                    var delta = now - dtInit;
                    Console.WriteLine("CurTime drift: {0:0.00} s", delta.TotalSeconds - (curTime - curTimeInit));
                    Console.WriteLine("TIME() drift: {0:0.00} ms", delta.TotalMilliseconds - (time - timeInit));
                    Console.WriteLine("PC2 drift: {0:0.00} ms", (delta - (GetNetworkTime() - pc2Init)).TotalMilliseconds);
                    Console.WriteLine("{0}", delta);
                    Thread.Sleep(50);
                }
            }
        }