tcp 读取plc下位机的简单连接，读取，修改方法 （ASCII 码方式）

 //创建接收信息的数组和客户端实例

        private static byte[] result = new byte[1024];

        IPAddress ip = IPAddress.Parse("192.168.1.11");

        int port1 = 10011;

        Socket clientsocket1 = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

        //连接服务器方法

        public void conn()

        {

            try

            {

                clientsocket1.Connect(new IPEndPoint(ip, port1));                

            }

            catch

            {

                clientsocket1.Shutdown(SocketShutdown.Both);

                clientsocket1.Close();
            }

      }

       //获取2000到2003数据

                clientsocket1.Send(Encoding.ASCII.GetBytes("500000FF03FF000018001004010000W*0020000004"));

                int receiveLength1 = clientsocket1.Receive(result);

                s1 = Encoding.ASCII.GetString(result, 0, receiveLength1);

        public void writeW1A1()

        {

            clientsocket1.Send(Encoding.ASCII.GetBytes("500000FF03FF00001C001014010000W*00001A00010001"));//改写w1A为1

            int receiveLength3 = clientsocket1.Receive(result);

        }