C# 使用modbus 读取PLC 寄存器地址的方法

使用的组件nmodbus

定义参数，全局变量：

//创建modbus实体对象        private static modbusfactory modbusfactory;
        private static imodbusmaster master;
        //写线圈或写寄存器数组
        bool[] coilsbuffer;
        ushort[] registerbuffer;
        //功能码
        string functioncode;
        //参数(分别为站号,起始地址,长度)
        byte slaveaddress;
        ushort startaddress;
        ushort numberofpoints;

        //ip 地址与端口号
        string ipaddress = string.empty;
        int visitport = 502;

初始化参数，创建连接：

private void connection(object sender, eventargs e)
         {
          try
           {
                //plc连接配置信息，plc ip地址
                ipaddress =127.0.0.1;                //端口，modbus 默认502，根据实际情况填写
                visitport =502;

                //初始化modbusmaster
                modbusfactory = new modbusfactory();
                //在本地测试 所以使用回环地址,modbus协议规定端口号 502
                master = modbusfactory.createmaster(new tcpclient(ipaddress, visitport));
                //设置读取超时时间
                master.transport.readtimeout = 10000;
                master.transport.retries = 2000;  
            }
            catch (exception ex)
            {
              messagebox.show(ex.message);
            }
        }

初始化读写参数

/// <summary>
        /// 初始化读参数
        /// </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);           //数据长度
           numberofpoints = ushort.parse(numberofpoints);            
        }

运行读取方法

private async void executefunction()
        {
            try
            {             //moddbus共有这些功能码               //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"；//根据实际点号类型选择读写功能码
                //重新实例化是为了 modbus slave更换连接时不报错 
                //master = modbusfactory.createmaster(new tcpclient(ipaddress, visitport));
                if (functioncode != null)
                {
                    switch (functioncode)
                    {
                        case "01 read coils"://读取单个线圈
                            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"://读取输入线圈/离散量线圈
                            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"://读取保持寄存器
                            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"://读取输入寄存器
                            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"://写单个线圈
                            setwriteparametes();
                            await master.writesinglecoilasync(slaveaddress, startaddress, coilsbuffer[0]);
                            break;
                        case "06 write single registers"://写单个输入线圈/离散量线圈
                            setwriteparametes();
                            await master.writesingleregisterasync(slaveaddress, startaddress, registerbuffer[0]);
                            break;
                        case "0f write multiple coils"://写一组线圈
                            setwriteparametes();
                            await master.writemultiplecoilsasync(slaveaddress, startaddress, coilsbuffer);
                            break;
                        case "10 write multiple registers"://写一组保持寄存器
                            setwriteparametes();
                            await master.writemultipleregistersasync(slaveaddress, startaddress, registerbuffer);
                            break;
                        default:
                            break;
                    }

                }
                else
                {
                    messagebox.show("请选择功能码!");
                }
                master.dispose();
            }
            catch (exception ex)
            {

                messagebox.show(ex.message);
            }
        }

//展示消息

/// <summary>
        /// setmessage
        /// </summary>
        /// <param name="msg"></param>
        public void setmsg(string msg)
        {     
            messagebox.show(msg);
        }

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