//創(chuàng)建modbus實體對象        private static ModbusFactory modbusFactory;
        private static IModbusMaster master;
        //寫線圈或寫寄存器數(shù)組
        bool[] coilsBuffer;
        ushort[] registerBuffer;
        //功能碼
        string functionCode;
        //參數(shù)(分別為站號,起始地址,長度)
        byte slaveAddress;
        ushort startAddress;
        ushort numberOfPoints;

        //ip 地址與端口號
        string IPAddress = string.Empty;
        int VisitPort = 502;

private void Connection(object sender, EventArgs e)
         {
          try
           {
                //PLC連接配置信息，PLC ip地址
                IPAddress =127.0.0.1;                //端口，modbus 默認502，根據實際情況填寫
                VisitPort =502;

                //初始化modbusmaster
                modbusFactory = new ModbusFactory();
                //在本地測試 所以使用回環(huán)地址,modbus協(xié)議規(guī)定端口號 502
                master = modbusFactory.CreateMaster(new TcpClient(IPAddress, VisitPort));
                //設置讀取超時時間
                master.Transport.ReadTimeout = 10000;
                master.Transport.Retries = 2000;  
            }
            catch (Exception ex)
            {
              MessageBox.Show(ex.Message);
            }
        }

/// <summary>
        /// 初始化讀參數(shù)
        /// </summary>
        private void SetReadParameters(int slaveAddress=1,int startAddress=200,int numberOfPoints=1)
        {           //DeviceID
           slaveAddress = byte.Parse(slaveAddress);           //起始地址，
           startAddress = ushort.Parse(startAddress);           //數(shù)據長度
           numberOfPoints = ushort.Parse(numberOfPoints);            
        }

private async void ExecuteFunction()
        {
            try
            {             //Moddbus共有這些功能碼               //01 Read Coils               //02 Read DisCrete Inputs               //03 Read Holding Registers               //04 Read Input Registers               //05 Write Single Coil               //06 Write Single Registers               //0F Write Multiple Coils               //10 Write Multiple Registers                 functionCode="01 Read Coils"；//根據實際點號類型選擇讀寫功能碼
                //重新實例化是為了 modbus slave更換連接時不報錯 
                //master = modbusFactory.CreateMaster(new TcpClient(IPAddress, VisitPort));
                if (functionCode != null)
                {
                    switch (functionCode)
                    {
                        case "01 Read Coils"://讀取單個線圈
                            SetReadParameters();
                            coilsBuffer = master.ReadCoils(slaveAddress, startAddress, numberOfPoints);

                            for (int i = 0; i < coilsBuffer.Length; i++)
                            {
                                SetMsg(coilsBuffer[i] + " ");
                            }
                            SetMsg("\r\n");
                            break;
                        case "02 Read DisCrete Inputs"://讀取輸入線圈/離散量線圈
                            SetReadParameters();

                            coilsBuffer = master.ReadInputs(slaveAddress, startAddress, numberOfPoints);
                            for (int i = 0; i < coilsBuffer.Length; i++)
                            {
                                SetMsg(coilsBuffer[i] + " ");
                            }
                            SetMsg("\r\n");
                            break;
                        case "03 Read Holding Registers"://讀取保持寄存器
                            SetReadParameters();
                            registerBuffer = master.ReadHoldingRegisters(slaveAddress, startAddress, numberOfPoints);
                            for (int i = 0; i < registerBuffer.Length; i++)
                            {
                                SetMsg(registerBuffer[i] + " ");
                            }
                            SetMsg("\r\n");
                            break;
                        case "04 Read Input Registers"://讀取輸入寄存器
                            SetReadParameters();
                            registerBuffer = master.ReadInputRegisters(slaveAddress, startAddress, numberOfPoints);
                            for (int i = 0; i < registerBuffer.Length; i++)
                            {
                                SetMsg(registerBuffer[i] + " ");
                            }
                            SetMsg("\r\n");
                            break;
                        case "05 Write Single Coil"://寫單個線圈
                            SetWriteParametes();
                            await master.WriteSingleCoilAsync(slaveAddress, startAddress, coilsBuffer[0]);
                            break;
                        case "06 Write Single Registers"://寫單個輸入線圈/離散量線圈
                            SetWriteParametes();
                            await master.WriteSingleRegisterAsync(slaveAddress, startAddress, registerBuffer[0]);
                            break;
                        case "0F Write Multiple Coils"://寫一組線圈
                            SetWriteParametes();
                            await master.WriteMultipleCoilsAsync(slaveAddress, startAddress, coilsBuffer);
                            break;
                        case "10 Write Multiple Registers"://寫一組保持寄存器
                            SetWriteParametes();
                            await master.WriteMultipleRegistersAsync(slaveAddress, startAddress, registerBuffer);
                            break;
                        default:
                            break;
                    }

                }
                else
                {
                    MessageBox.Show("請選擇功能碼!");
                }
                master.Dispose();
            }
            catch (Exception ex)
            {

                MessageBox.Show(ex.Message);
            }
        }

/// <summary>
        /// SetMessage
        /// </summary>
        /// <param name="msg"></param>
        public void SetMsg(string msg)
        {     
            MessageBox.Show(msg);
        }