一、什么是ModBus通讯协议

　　Modbus协议是应用于电子控制器上的一种通用语言，此协议支持传统的RS-232、RS-422、RS-485和以太网设备。

　　ModBus功能码

01	READ COIL STATUS
02	READ INPUT STATUS
03	READ HOLDING REGISTER
04	READ INPUT REGISTER
05	WRITE SINGLE COIL
06	WRITE SINGLE REGISTER
15	WRITE MULTIPLE COIL
16	WRITE MULTIPLE REGISTER

二、ModBus通讯协议的.Net实现

　　　　推荐一个github的开源实现类库：NModBus，github地址：https://github.com/NModbus/NModbus。针对TCP、UDP、RTU等的ModBus通讯方式都有实现。

　　　　读写方法：

方法名	作用	所需参数	返回值	对应功能码
ReadCoils	读取DO的状态	从站地址(8位) byte slaveAddress 起始地址(16位) ushort startAddress 读取数量(16位) ushort numberOfPoints	bool[]	01
ReadInputs	读取DI的状态	从站地址(8位) byte slaveAddress 起始地址(16位) ushort startAddress 读取数量(16位) ushort numberOfPoints	bool[]	02
ReadHoldingRegisters	读取AO的值	从站地址(8位) byte slaveAddress 起始地址(16位)  ushort startAddress 读取数量(16位) ushort numberOfPoints	ushort[]	03
ReadInputRegisters	读取AI的值	从站地址(8 位) byte slaveAddress 起始地址(16位) ushort startAddress 读取数量(16位) ushort numberOfPoints	ushort[]	04
WriteSingleCoil	写入值到DO	从站地址(8位) byte slaveAddress 线圈地址(16位) ushort coilAddress 写入值(布尔型) bool value	无返回值	05
WriteSingleRegister	写入值到AO	从站地址(8位) byte slaveAddress 寄存器地址(16位) ushort registerAddress 写入值(16位) ushort value	无返回值	06
WriteMultipleCoils	写多线圈寄存器	从站地址(8位) byte slaveAddress 起始地址(16位) ushort startAddress 写入值(布尔型数组) bool[] data	无返回值	15
WriteMultipleRegisters	写多个保持寄存器	从站地址(8位) byte slaveAddress 起始地址(16位) ushort startAddress, 寄存器值(16位整型数组) ushort[] data	无返回值	16
ReadWriteMultipleRegisters	读写多个保持寄存器	从站地址(8位) byte slaveAddress 读起始地址(16位) ushort startReadAddress 读取数量(16位) ushort numberOfPointsToRead, 写入起始地址(16位) ushort startWriteAddress, 写入值(16位整型数组) ushort[] writeData	ushort[]	23

　　　　每个方法都有各自的异步方法实现。

三、NModBus Master 示例

 

 

private static void Main(string[] args)

        {

            try

            {

                ModbusSerialRtuMasterWriteRegisters();

                ModbusTcpMasterReadInputs();

            }

            catch (Exception e)

            {

                Console.WriteLine(e.Message);

            }



            Console.WriteLine("Press any key to continue...");

            Console.ReadKey();

        }



        /// <summary>

        /// Simple Modbus serial RTU master write holding registers example.

        /// </summary>

        public static void ModbusSerialRtuMasterWriteRegisters()

        {

            using (SerialPort port = new SerialPort("COM3"))

            {

                // configure serial port

                port.BaudRate = 9600;

                port.DataBits = 8;

                port.Parity = Parity.None;

                port.StopBits = StopBits.One;

                port.Open();



                var factory = new ModbusFactory();

                IModbusMaster master = factory.CreateRtuMaster(port);



                byte slaveId = 1;

                ushort startAddress = 100;

                ushort[] registers = new ushort[] { 1, 2, 3 };



                // write three registers

                master.WriteMultipleRegisters(slaveId, startAddress, registers);

            }

        }



        /// <summary>

        ///     Simple Modbus TCP master read inputs example.

        /// </summary>

        public static void ModbusTcpMasterReadInputs()

        {

            using (TcpClient client = new TcpClient("127.0.0.1", 502))

            {

                var factory = new ModbusFactory();

                IModbusMaster master = factory.CreateMaster(client);



                // read five input values

                ushort startAddress = 100;

                ushort numInputs = 5;

                bool[] inputs = master.ReadInputs(0, startAddress, numInputs);



                for (int i = 0; i < numInputs; i++)

                {

                    Console.WriteLine($"Input {(startAddress + i)}={(inputs[i] ? 1 : 0)}");

                }

            }



            // output:

            // Input 100=0

            // Input 101=0

            // Input 102=0

            // Input 103=0

            // Input 104=0

        }

using NModbus;
using NModbus.Serial;//安装库
using System.IO.Ports;

private void button3_Click(object sender, EventArgs e)
{
    using (SerialPort port = new SerialPort("COM6"))

    {

        // configure serial port

        port.BaudRate = 9600;

        port.DataBits = 8;

        port.Parity = Parity.None;

        port.StopBits = StopBits.One;

        port.WriteTimeout = 1000;

        port.Open();


        var factory = new ModbusFactory();
        IModbusMaster master = factory.CreateRtuMaster(new SerialPortAdapter(port));
       string A =master.ReadHoldingRegisters(1, 0, 1)[0].ToString();
        MessageBox.Show(A);
    }
}

 转载自：

https://www.cnblogs.com/YourDirection/category/1621822.htmlhttps://www.cnblogs.com/YourDirection/category/1621822.html

https://www.cnblogs.com/YourDirection/p/15187308.htmlhttps://www.cnblogs.com/YourDirection/p/15187308.html