【C#】CS学习之Modbus通讯

摘要
本文详细描述了如何在在C#的Winform应用程序中使用NModbus库实现Modbus通讯，包括读取保持寄存器、以及相应的UI界面设计和事件处理。

前言

应用场景

Modbus 从站广泛应用于工业自动化领域：
1、传感器数据采集（如温度、压力等）
2、执行器控制（如电机、阀门等）
3、设备监控与故障诊断。

Modbus 从站（Slave）是 Modbus 通信协议中的响应设备，负责接收并执行来自主站（Master）的请求。

Modbus 从站是被动设备，它不能主动发起通信，只能响应主站的请求。从站的主要功能包括：
1、接收主站的指令（如读取数据或执行操作）。
2、执行相应的操作（如读取寄存器值或设置参数）。
3、返回响应数据或错误码给主站。

通信模式

Modbus 从站支持多种通信模式：
1、Modbus RTU/ASCII：通过串口（如 RS485）进行通信，从站监听串口链路并响应主站指令。
2、Modbus TCP：通过以太网进行通信，从站作为服务器监听 TCP 端口（默认 502 端口）并处理客户端请求。

寄存器类型

Modbus 从站通常管理四种类型的寄存器：
1、线圈（Coils）：可读写的二进制状态（如开关状态）。
2、离散输入（Discrete Inputs）：只读的二进制状态。
3、保持寄存器（Holding Registers）：可读写的16位数据。
4、输入寄存器（Input Registers）：只读的16位数据。

实现步骤

1、创建TcpListener并启动侦听
2、创建Modbus从站数据存储
3、初始化数据
4、创建Modbus从站
5、创建Modbus TCP从站网络
6、添加从站到网络
7、异步侦听网络

运行结果

在这里插入图片描述

代码

Frm_ModbusService

    public partial class Frm_ModbusService : Form{#region 字段//定时器Timer timer = null;ModbusService modbusService = null;#endregion#region 构造函数、初始化public Frm_ModbusService(){InitializeComponent();CenterToParent();CenterToScreen();}private void ModbusService_Load(object sender, EventArgs e){Initialize();}private void ModbusService_FormClosing(object sender, FormClosingEventArgs e){modbusService.Stop();}#endregion/// <summary>/// 初始化控件状态/// </summary>public void InitializeControlsState(){tbx_IPAddress.Text = modbusService.IpAddress.ToString();tbx_OpenPort.Text = modbusService.Port.ToString();tbx_StartAddress.Text = modbusService.StartAddress.ToString();tbx_SlaveID.Text = modbusService.SlaveId.ToString();  }/// <summary>/// 初始化/// </summary>public void Initialize(){modbusService = new ModbusService();modbusService.MessageUpdateHandler += OnUpdataMessage;InitializeControlsState();UpdataControlsState(modbusService.IsRunning);timer = new Timer();timer.Interval = 100;timer.Tick += Timer_Tick;dataGridView.Columns[0].Width = 100;dataGridView.Columns[1].Width = 100;dataGridView.Columns[0].DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter;dataGridView.Columns[1].DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter;dataGridView.RowHeadersVisible = false;//10行dataGridView.Rows.Add(new object[] { 0, 0});dataGridView.Rows.Add(new object[] { 1, 0 });dataGridView.Rows.Add(new object[] { 2, 0 });dataGridView.Rows.Add(new object[] { 3, 0 });dataGridView.Rows.Add(new object[] { 4, 0 });dataGridView.Rows.Add(new object[] { 5, 0 });dataGridView.Rows.Add(new object[] { 6, 0 });dataGridView.Rows.Add(new object[] { 7, 0 });dataGridView.Rows.Add(new object[] { 8, 0 });dataGridView.Rows.Add(new object[] { 9, 0 });}/// <summary>/// 定时器方法/// </summary>private void Timer_Tick(object sender, EventArgs e){var array = modbusService.DataStore.HoldingRegisters.ReadPoints(modbusService.StartAddress, 10);for (int i = 0; i < array.Length; i++){dataGridView.Rows[i].Cells[0].Value = (modbusService.StartAddress+ i);dataGridView.Rows[i].Cells[1].Value = array[i];}}/// <summary>/// 启动按钮/// </summary>private void btn_Start_Click(object sender, EventArgs e){try{if (!modbusService.IsRunning){modbusService.Start();timer.Start();UpdataControlsState(modbusService.IsRunning);}else{modbusService.Stop();timer.Stop();UpdataControlsState(modbusService.IsRunning);UpdataMessage("Modbus服务停止");}}catch (Exception ex){modbusService.Stop();timer.Stop();UpdataControlsState(modbusService.IsRunning);UpdataMessage($"Modbus服务异常停止:{ex.Message}");}}/// <summary>/// 更新消息/// </summary>private void UpdataMessage(string message){tbx_Output.BeginInvoke(new Action(() =>{if (tbx_Output.Lines.Length>100){tbx_Output.Clear();}tbx_Output.AppendText($"{DateTime.Now.ToString()}】{message}\r\n");}));}/// <summary>/// 更新消息/// </summary>private void OnUpdataMessage(object sender, string message){UpdataMessage(message);}/// <summary>/// 更新控件状态/// </summary>private void UpdataControlsState(bool isRunning){if (isRunning){tbx_IPAddress.Enabled = false;tbx_OpenPort.Enabled = false;tbx_SlaveID.Enabled = false;btn_Start.Text = "关闭";}else{tbx_IPAddress.Enabled = true;tbx_OpenPort.Enabled = true;tbx_SlaveID.Enabled = true;btn_Start.Text = "启动";}}#region 参数变更/// <summary>/// IP地址变更/// </summary>private void tbxIPAddress_TextChanged(object sender, EventArgs e){if (IPAddress.TryParse(tbx_IPAddress.Text,out IPAddress result)){modbusService.IpAddress = result;}else{tbx_IPAddress.Text = modbusService.IpAddress.ToString();}}/// <summary>/// 端口变更/// </summary>private void tbxOpenPort_TextChanged(object sender, EventArgs e){if (ushort.TryParse(tbx_OpenPort.Text, out ushort result)){modbusService.Port = result;}else{tbx_OpenPort.Text = modbusService.Port.ToString();}}/// <summary>/// 起始地址变更/// </summary>private void tbx_StartAddress_TextChanged(object sender, EventArgs e){if (ushort.TryParse(tbx_StartAddress.Text, out ushort result)){modbusService.StartAddress = result;}else{tbx_StartAddress.Text = modbusService.StartAddress.ToString();}}/// <summary>/// 站ID变更/// </summary>private void tbx_SlaveID_TextChanged(object sender, EventArgs e){if (byte.TryParse(tbx_SlaveID.Text, out byte result)){modbusService.SlaveId = result;}else{tbx_SlaveID.Text = modbusService.SlaveId.ToString();}}#endregion}
}

ModbusService

public class ModbusService
{#region 字段、属性public event EventHandler<string> MessageUpdateHandler;private IPAddress ipAddress = IPAddress.Parse("127.0.0.1");private int port = 502;    			//端口private byte slaveId = 1;    		// 从站地址private ushort startAddress = 0;    //起始地址private bool isRunning = false;     //运行状态private TcpListener tcpListener = null;    			//创建Modbus服务器private DefaultSlaveDataStore dataStore = null;    //默认从站数据存储private ModbusFactory factory = null;    			//Bodbus工厂private IModbusSlave slave = null;    			//modbus从站IModbusTcpSlaveNetwork slaveNetwork = null;    	//ModbusTcp从站网络public IPAddress IpAddress { get => ipAddress; set => ipAddress = value; }public int Port { get => port; set => port = value; }public byte SlaveId { get => slaveId; set => slaveId = value; }public ushort StartAddress { get => startAddress; set => startAddress = value; }public bool IsRunning { get => isRunning; set => isRunning = value; }public TcpListener TcpListener { get => tcpListener; set => tcpListener = value; }public DefaultSlaveDataStore DataStore { get => dataStore; set => dataStore = value; }public ModbusFactory Factory { get => factory; set => factory = value; }public IModbusSlave Slave { get => slave; set => slave = value; }public IModbusTcpSlaveNetwork SlaveNetwork { get => slaveNetwork; set => slaveNetwork = value; }#endregionpublic ModbusService() {}/// <summary>/// 初始化从站数据存储/// </summary>private void InitializeDataStore(DefaultSlaveDataStore dataStore){// 初始化保持寄存器dataStore.HoldingRegisters.WritePoints(0, new ushort[] { 0 });// 初始化输入寄存器dataStore.InputRegisters.WritePoints(0, new ushort[] { 0 });// 初始化线圈dataStore.CoilDiscretes.WritePoints(0, new bool[] { false });// 初始化离散输入dataStore.CoilInputs.WritePoints(0, new bool[] { false });}/// <summary>/// 启动按钮/// </summary>public void Start(){try{if (!IsRunning){// 创建TcpListener并启动TcpListener = new TcpListener(IpAddress, Port);//启动侦听TcpListener.Start();// 创建Modbus从站数据存储DataStore = new DefaultSlaveDataStore();// 初始化数据InitializeDataStore(DataStore);// 创建Modbus从站Factory = new ModbusFactory();Slave = Factory.CreateSlave(1, DataStore);// 创建Modbus TCP从站网络SlaveNetwork = Factory.CreateSlaveNetwork(TcpListener);// 添加从站到网络SlaveNetwork.AddSlave(Slave);//异步侦听网络SlaveNetwork.ListenAsync();IsRunning = true;OnUpdataMessage("Modbus服务启动");}}catch (Exception ex){Stop();OnUpdataMessage($"Modbus服务异常停止:{ex.Message}");}}public void Stop(){TcpListener?.Stop();SlaveNetwork?.Dispose();DataStore = null;Factory = null;Slave = null;IsRunning = false;}/// <summary>/// 消息更新/// </summary>private void OnUpdataMessage(string message){MessageUpdateHandler?.Invoke(this,message);}
}