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一、前言

Modbus是一种串行通信协议，是工业领域全球最流行的协议之一。

1.1 环境

系统：Win11
工具：Visual Studio 2022
.Net 版本：.Net Framework4.6.0
依赖库：NModbus 3.0.81

1.2 协议类型

Modbus RTU：一种二进制协议，采用紧凑的数据帧格式，通信效率较高。通常用于串行通信链路，如RS - 485或RS - 232 ，在工业自动化领域应用广泛。

Modbus ASCII：采用ASCII码进行数据传输，数据帧可读性强，但传输效率相对较低，同样基于串行通信。

​Modbus TCP/IP：基于以太网和TCP/IP协议栈，将Modbus协议封装在TCP/IP协议中，适用于通过网络进行远程通信的场合，是目前工业以太网中常用的通信协议之一。

1.3 通信模式

​主从模式：在Modbus网络中，有一个主设备（通常是控制器或上位机）和多个从设备（如传感器、执行器等）。主设备发起通信请求，从设备根据请求进行响应，从设备不能主动向主设备发送数据。

1.4 程序功能

1、连接从站服务。
2、写入数值到指定寄存器
3、定时读取寄存器值
4、定时心跳检测通讯状态。

二、运行界面

三、代码

public partial class ModbusTCP : Form
{#region 字段// Modbus服务器的IP地址和端口private string ipAddress = "127.0.0.1";// 端口号private int port = 502;// 从站地址private byte slaveId = 1;// 读取保持寄存器的起始地址和数量ushort startAddress = 0;ushort numRegisters = 10;// 写入寄存器的地址和值ushort writeAddress = 0;ushort writeValue = 0;// 连接状态private bool isConnected = false;// 创建TcpClientprivate TcpClient tcpClient = null;// 创建modbusprivate ModbusFactory factory = null;// Modbus主站private IModbusMaster master = null;// 任务定时器Timer taskTimer = null;// 心跳定时器private Timer heartbeatTimer = null;#endregion#region 初始化加载public ModbusTCP(){InitializeComponent();CenterToParent();CenterToScreen();}private void MainForm_Load(object sender, EventArgs e){Initialize();}private void ModbusTCP_FormClosing(object sender, FormClosingEventArgs e){isConnected = false;taskTimer?.Stop();tcpClient?.Close();heartbeatTimer?.Stop();}#endregion/// <summary>/// 初始化/// </summary>public void Initialize(){InitializeControlsState();UpdataControlsState();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;//数据表格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 });//定时读取值taskTimer = new Timer();taskTimer.Interval = 100;taskTimer.Tick += Timer_Tick;// 心跳任务heartbeatTimer = new Timer();heartbeatTimer.Interval = 1000;heartbeatTimer.Tick += HeartbeatTimer_Tick;}private void HeartbeatTimer_Tick(object sender, EventArgs e){try{// 发送心跳请求（这里假设发送一个简单的读取请求作为心跳）ushort[] dummyArray = master.ReadHoldingRegisters(slaveId, 0, 1);// 检查心跳响应是否有效（可以根据返回值来判断）if (dummyArray == null || dummyArray.Length != 1 || dummyArray[0] != 0){UpdataMessage("心跳失败，断开连接...");isConnected = false;taskTimer.Stop();tcpClient.Close();UpdataControlsState();}}catch (Exception ex){UpdataMessage("心跳失败...");isConnected = false;taskTimer.Stop();tcpClient.Close();UpdataControlsState();}}/// <summary>/// 初始化控件状态/// </summary>public void InitializeControlsState(){tbx_SlaveID.Text = slaveId.ToString();tbx_IPAddress.Text = ipAddress;tbx_TargetPort.Text = port.ToString();tbx_StartAddress.Text = startAddress.ToString();tbx_ReadLength.Enabled = false;tbx_ReadLength.Text = numRegisters.ToString();tbx_WriteAddress.Text = writeAddress.ToString();tbx_WriteValue.Text = writeValue.ToString();}private void UpdataControlsState(){if (isConnected){btn_Connect.Text = "断开";btn_WriteData.Enabled = true;tbx_IPAddress.Enabled = false;tbx_TargetPort.Enabled = false;tbx_SlaveID.Enabled = false;tbx_ReadLength.Enabled=false;}else{btn_Connect.Text = "连接";btn_WriteData.Enabled = false;tbx_IPAddress.Enabled = true;tbx_TargetPort.Enabled = true;tbx_SlaveID.Enabled = true;tbx_ReadLength.Enabled = false;}}/// <summary>/// 定时器方法/// </summary>private void Timer_Tick(object sender, EventArgs e){try{if (isConnected){// 读取保持寄存器ushort[] array = master.ReadHoldingRegisters(slaveId, startAddress, numRegisters);// 输出读取到的寄存器值for (int i = 0; i < array.Length; i++){dataGridView.Rows[i].Cells[0].Value = (startAddress + i);dataGridView.Rows[i].Cells[1].Value = array[i];}}}catch (Exception ex){UpdataMessage("");}}/// <summary>///  连接/// </summary>private void btn_Connect_Click(object sender, EventArgs e){try{if (!isConnected){tcpClient = new TcpClient(ipAddress, port);factory = new ModbusFactory();master = factory.CreateMaster(tcpClient);taskTimer.Start();heartbeatTimer?.Start();isConnected = true;UpdataControlsState();UpdataMessage("连接成功...");}else{isConnected = false;master = null;taskTimer.Stop();tcpClient.Close();UpdataControlsState();UpdataMessage("断开连接...");heartbeatTimer?.Stop();}}catch (Exception ex){isConnected = false;taskTimer?.Stop();heartbeatTimer?.Stop();tcpClient?.Close();UpdataControlsState();UpdataMessage("连接失败...");UpdataMessage($"{ex.Message}");}}/// <summary>///  写入数据/// </summary>private void btn_WriteData_Click(object sender, EventArgs e){master.WriteSingleRegister(slaveId, writeAddress, writeValue);UpdataMessage($"从站ID：{slaveId}，写入数据：地址：{writeAddress} ，值:{writeValue}");}/// <summary>/// 更新操作消息/// </summary>private void UpdataMessage(string message){tbx_Output.BeginInvoke(new Action(() =>{tbx_Output.AppendText($"{DateTime.Now.ToString()}】{message}\r\n");}));}#region 文本变更/// <summary>/// 起始地址/// </summary>private void tbx_StartAddress_TextChanged(object sender, EventArgs e){if (ushort.TryParse(tbx_StartAddress.Text, out ushort address)){startAddress = address;}}/// <summary>/// 读取长度/// </summary>private void tbx_ReadLength_TextChanged(object sender, EventArgs e){if (ushort.TryParse(tbx_ReadLength.Text, out ushort length)){numRegisters = length;}}/// <summary>/// 写入地址/// </summary>private void tbx_WriteAddress_TextChanged(object sender, EventArgs e){if (ushort.TryParse(tbx_WriteAddress.Text, out ushort address)){writeAddress = address;}}/// <summary>/// 写入值/// </summary>private void tbx_WriteValue_TextChanged(object sender, EventArgs e){if (ushort.TryParse(tbx_WriteValue.Text, out ushort address)){writeValue = address;}}/// <summary>/// 从站ID/// </summary>private void tbx_SlaveID_TextChanged(object sender, EventArgs e){if (byte.TryParse(tbx_SlaveID.Text, out byte address)){slaveId = address;}}#endregion
}