C# NModbus RTU通信实现方法详解
作者：熊来闯一闯
Modbus协议时应用于电子控制器上的一种通用语言,通过此协议,控制器相互之间、控制器经由网络/串口和其它设备之间可以进行通信,下面我们就来看看具体实现吧
Modbus协议时应用于电子控制器上的一种通用语言。通过此协议，控制器相互之间、控制器经由网络/串口和其它设备之间可以进行通信。它已经成为了一种工业标准。有了这个通信协议，不同的厂商生成的控制设备就可以连城工业网络，进行集中监控。
本文实现需要借用一个开源的NModbus库来完成，通过在菜单栏，工具-----NuGet包管理器-----管理解决方案的NuGet程序包，安装NModbus的开源库。
本次实例的基本框架和实现效果如下所示：
可自动识别当前设备的可用串口。
Modbus RTU通信的具体的实现如下：
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Modbus.Device;
using System.Net.Sockets;
using System.Threading;
using System.IO.Ports;
using System.Drawing.Text;
using System.Windows.Forms.VisualStyles;
using System.Timers;
using System.CodeDom.Compiler;
namespace ModbusRtuMaster
{
public partial class Form1 : Form
{
#region 参数配置
private static IModbusMaster master;
private static SerialPort port;
//写线圈或写寄存器数组
private bool[] coilsBuffer;
private ushort[] registerBuffer;
//功能码
private string functionCode;
//功能码序号
private int functionOder;
//参数(分别为从站地址,起始地址,长度)
private byte slaveAddress;
private ushort startAddress;
private ushort numberOfPoints;
//串口参数
private string portName;
private int baudRate;
private Parity parity;
private int dataBits;
private StopBits stopBits;
//自动测试标志位
private bool AutoFlag = false;
//获取当前时间
private System.DateTime Current_time;
//定时器初始化
private System.Timers.Timer t = new System.Timers.Timer(1000);
private const int WM_DEVICE_CHANGE = 0x219; //设备改变
private const int DBT_DEVICEARRIVAL = 0x8000; //设备插入
private const int DBT_DEVICE_REMOVE_COMPLETE = 0x8004; //设备移除
#endregion
public Form1()
{
InitializeComponent();
GetSerialLstTb1();
}
private void Form1_Load(object sender, EventArgs e)
{
//界面初始化
cmb_portname.SelectedIndex = 0;
cmb_baud.SelectedIndex = 5;
cmb_parity.SelectedIndex = 2;
cmb_databBits.SelectedIndex = 1;
cmb_stopBits.SelectedIndex = 0;
}
#region 定时器
//定时器初始化,失能状态
private void init_Timer()
{
t.Elapsed += new System.Timers.ElapsedEventHandler(Execute);
t.AutoReset = true;//设置false定时器执行一次，设置true定时器一直执行
t.Enabled = false;//定时器使能true，失能false
//t.Start();
}
private void Execute(object source,System.Timers.ElapsedEventArgs e)
{
//停止定时器后再打开定时器，避免重复打开
t.Stop();
//ExecuteFunction();可添加执行操作
t.Start();
}
#endregion
#region 串口配置
/// <summary>
/// 串口参数获取
/// </summary>
/// <returns></返回串口配置参数>
private SerialPort InitSerialPortParameter()
{
if (cmb_portname.SelectedIndex < 0 || cmb_baud.SelectedIndex < 0 || cmb_parity.SelectedIndex < 0 || cmb_databBits.SelectedIndex < 0 || cmb_stopBits.SelectedIndex < 0)
{
MessageBox.Show("请选择串口参数");
return null;
}
else
{
portName = cmb_portname.SelectedItem.ToString();
baudRate = int.Parse(cmb_baud.SelectedItem.ToString());
switch (cmb_parity.SelectedItem.ToString())
{
case "奇":
parity = Parity.Odd;
break;
case "偶":
parity = Parity.Even;
break;
case "无":
parity = Parity.None;
break;
default:
break;
}
dataBits = int.Parse(cmb_databBits.SelectedItem.ToString());
switch (cmb_stopBits.SelectedItem.ToString())
{
case "1":
stopBits = StopBits.One;
break;
case "2":
stopBits = StopBits.Two;
break;
default:
break;
}
port = new SerialPort(portName, baudRate, parity, dataBits, stopBits);
return port;
}
}
#endregion
#region 串口收/发
private async void ExecuteFunction()
{
Current_time = System.DateTime.Now;
try
{
if (port.IsOpen == false)
{
port.Open();
}
if (functionCode != null)
{
switch (functionCode)
{
case "01 Read Coils"://读取单个线圈
SetReadParameters();
try
{
coilsBuffer = master.ReadCoils(slaveAddress, startAddress, numberOfPoints);
}
catch(Exception)
{
MessageBox.Show("参数配置错误");
//MessageBox.Show(e.Message);
AutoFlag = false;
break;
}
SetMsg("[" + Current_time.ToString("yyyy-MM-dd HH:mm:ss" + "]" + " "));
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();
try
{
coilsBuffer = master.ReadInputs(slaveAddress, startAddress, numberOfPoints);
}
catch(Exception)
{
MessageBox.Show("参数配置错误");
AutoFlag = false;
break;
}
SetMsg("[" + Current_time.ToString("yyyy-MM-dd HH:mm:ss" + "]" + " "));
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();
try
{
registerBuffer = master.ReadHoldingRegisters(slaveAddress, startAddress, numberOfPoints);
}
catch (Exception)
{
MessageBox.Show("参数配置错误");
AutoFlag = false;
break;
}
SetMsg("[" + Current_time.ToString("yyyy-MM-dd HH:mm:ss" + "]" + " "));
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();
try
{
registerBuffer = master.ReadInputRegisters(slaveAddress, startAddress, numberOfPoints);
}
catch (Exception)
{
MessageBox.Show("参数配置错误");
AutoFlag = false;
break;
}
SetMsg("[" + Current_time.ToString("yyyy-MM-dd HH:mm:ss" + "]" + " "));
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!");
}
port.Close();
}
catch (Exception ex)
{
port.Close();
MessageBox.Show(ex.Message);
}
}
#endregion
/// <summary>
/// 设置读参数
/// </summary>
private void SetReadParameters()
{
if (txt_startAddr1.Text == "" || txt_slave1.Text == "" || txt_length.Text == "")
{
MessageBox.Show("请填写读参数!");
}
else
{
slaveAddress = byte.Parse(txt_slave1.Text);
startAddress = ushort.Parse(txt_startAddr1.Text);
numberOfPoints = ushort.Parse(txt_length.Text);
}
}
/// <summary>
/// 设置写参数
/// </summary>
private void SetWriteParametes()
{
if (txt_startAddr2.Text == "" || txt_slave2.Text == "" || txt_data.Text == "")
{
MessageBox.Show("请填写写参数!");
}
else
{
slaveAddress = byte.Parse(txt_slave2.Text);
startAddress = ushort.Parse(txt_startAddr2.Text);
//判断是否写线圈
if (functionOder == 4 || functionOder == 6)
{
string[] strarr = txt_data.Text.Split(' ');
coilsBuffer = new bool[strarr.Length];
//转化为bool数组
for (int i = 0; i < strarr.Length; i++)
{
// strarr[i] == "0" ? coilsBuffer[i] = false : coilsBuffer[i] = true;
if (strarr[i] == "0")
{
coilsBuffer[i] = false;
}
else
{
coilsBuffer[i] = true;
}
}
}
else
{
//转化ushort数组
string[] strarr = txt_data.Text.Split(' ');
registerBuffer = new ushort[strarr.Length];
for (int i = 0; i < strarr.Length; i++)
{
registerBuffer[i] = ushort.Parse(strarr[i]);
}
}
}
}
/// <summary>
/// 创建委托，打印日志
/// </summary>
/// <param name="msg"></param>
public void SetMsg(string msg)
{
richTextBox1.Invoke(new Action(() => { richTextBox1.AppendText(msg); }));
}
/// <summary>
/// 清空日志
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button2_Click(object sender, EventArgs e)
{
richTextBox1.Clear();
}
/// <summary>
/// 单击button1事件，串口完成一次读/写操作
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button1_Click(object sender, EventArgs e)
{
//AutoFlag = false;
//button_AutomaticTest.Enabled = true;
try
{
//初始化串口参数
InitSerialPortParameter();
master = ModbusSerialMaster.CreateRtu(port);
ExecuteFunction();
}
catch (Exception)
{
MessageBox.Show("初始化异常");
}
}
/// <summary>
/// 自动测试初始化
/// </summary>
private void AutomaticTest()
{
AutoFlag = true;
button1.Enabled = false;
InitSerialPortParameter();
master = ModbusSerialMaster.CreateRtu(port);
Task.Factory.StartNew(() =>
{
//初始化串口参数
while (AutoFlag)
{
try
{
ExecuteFunction();
}
catch (Exception)
{
MessageBox.Show("初始化异常");
}
Thread.Sleep(500);
}
});
}
/// <summary>
/// 读取数据时，失能写数据；写数据时，失能读数据
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (comboBox1.SelectedIndex >= 4)
{
groupBox2.Enabled = true;
groupBox1.Enabled = false;
}
else
{
groupBox1.Enabled = true;
groupBox2.Enabled = false;
}
//委托事件,在主线程中创建的控件，在子线程中读取设置控件的属性会出现异常，使用Invoke方法可以解决
comboBox1.Invoke(new Action(() => { functionCode = comboBox1.SelectedItem.ToString(); functionOder = comboBox1.SelectedIndex; }));
}
/// <summary>
/// 将打印日志显示到最新接收到的符号位置
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void richTextBox1_TextChanged(object sender, EventArgs e)
{
this.richTextBox1.SelectionStart = int.MaxValue;
this.richTextBox1.ScrollToCaret();
}
/// <summary>
/// 自动化测试
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button_AutomaticTest_Click(object sender, EventArgs e)
{
AutoFlag = false;
button_AutomaticTest.Enabled = false; //自动收发按钮失能，避免从复开启线程
if (AutoFlag == false)
{
AutomaticTest();
}
}
/// <summary>
/// 串口关闭，停止读/写
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button_ClosePort_Click(object sender, EventArgs e)
{
AutoFlag = false;
button1.Enabled = true;
button_AutomaticTest.Enabled = true;
t.Enabled = false;//失能定时器
if (port.IsOpen)
{
port.Close();
}
}
#region 串口下拉列表刷新
/// <summary>
/// 刷新下拉列表显示
/// </summary>
private void GetSerialLstTb1()
{
//清除cmb_portname显示
cmb_portname.SelectedIndex = -1;
cmb_portname.Items.Clear();
//获取串口列表
string[] serialLst = SerialPort.GetPortNames();
if (serialLst.Length > 0)
{
//取串口进行排序
Array.Sort(serialLst);
//将串口列表输出到cmb_portname
cmb_portname.Items.AddRange(serialLst);
cmb_portname.SelectedIndex = 0;
}
}
/// <summary>
/// 消息处理
/// </summary>
/// <param name="m"></param>
protected override void WndProc(ref Message m)
{
switch (m.Msg) //判断消息类型
{
case WM_DEVICE_CHANGE: //设备改变消息
{
GetSerialLstTb1(); //设备改变时重新花去串口列表
}
break;
}
base.WndProc(ref m);
}
#endregion
private void label11_Click(object sender, EventArgs e)
{
}
private void txt_slave1_TextChanged(object sender, EventArgs e)
{
}
private void label7_Click(object sender, EventArgs e)
{
}
private void txt_startAddr1_TextChanged(object sender, EventArgs e)
{
}
private void label8_Click(object sender, EventArgs e)
{
}
private void txt_length_TextChanged(object sender, EventArgs e)
{
}
}
}在线程中对控件的属性进行操作可能会出现代码异常，可以使用Invoke委托方法完成相应的操作：
public void SetMsg(string msg)
{
richTextBox1.Invoke(new Action(() => { richTextBox1.AppendText(msg); }));
}在进行自动读/写操作时，为避免多次点击按键控件，多次重复建立新线程；在进入自动读写线程中时，将对应的按键控件失能，等待停止读写操作时再使能：
private void AutomaticTest()
{
AutoFlag = true;
button1.Enabled = false;
InitSerialPortParameter();
master = ModbusSerialMaster.CreateRtu(port);
Task.Factory.StartNew(() =>
{
//初始化串口参数
while (AutoFlag)
{
try
{
ExecuteFunction();
}
catch (Exception)
{
MessageBox.Show("初始化异常");
}
Thread.Sleep(500);
}
});
}自动获取当前设备的可用串口实现如下：
#region 串口下拉列表刷新
/// <summary>
/// 刷新下拉列表显示
/// </summary>
private void GetSerialLstTb1()
{
//清除cmb_portname显示
cmb_portname.SelectedIndex = -1;
cmb_portname.Items.Clear();
//获取串口列表
string[] serialLst = SerialPort.GetPortNames();
if (serialLst.Length > 0)
{
//取串口进行排序
Array.Sort(serialLst);
//将串口列表输出到cmb_portname
cmb_portname.Items.AddRange(serialLst);
cmb_portname.SelectedIndex = 0;
}
}
/// <summary>
/// 消息处理
/// </summary>
/// <param name="m"></param>
protected override void WndProc(ref Message m)
{
switch (m.Msg) //判断消息类型
{
case WM_DEVICE_CHANGE: //设备改变消息
{
GetSerialLstTb1(); //设备改变时重新花去串口列表
}
break;
}
base.WndProc(ref m);
}
#endregion对本次实例进行测试需要使用到串口模拟软件，串口模拟器可以到网上下载
Modbus从站需要完成一下两步操作：
一、菜单栏Connection-----Connect
二、菜单栏Setup-----Slave Definition
最后需要运行自己创建的Modbus RTU Master上位机，完成相应的配置：
实现的最终效果：
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