C#读取串口条码阅读器数据问题：DataReceived事件未触发

设备通过虚拟COM端口连接到COM3，在记事本、Excel中可正常读取数据，但自行开发的C# Windows窗体应用中BarCodeReader1_DataReceived事件始终未执行，代码如下：

using System;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO.Ports;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        SerialPort port = new SerialPort("COM3", 115200, Parity.None, 8, StopBits.One);

        public Form1()
        {
            InitializeComponent();
            BarCodeReader1.PortName = "COM3";
            BarCodeReader1.BaudRate = 115200;   // 19200;
            BarCodeReader1.Parity = Parity.None;
            BarCodeReader1.DataBits = 8;
            BarCodeReader1.StopBits = StopBits.One;
            BarCodeReader1.Handshake = Handshake.None;
            BarCodeReader1.RtsEnable = true;
        }

        private void cmd_Exit_Click(object sender, EventArgs e)
        {
            if ((BarCodeReader1.IsOpen))
                BarCodeReader1.Close();

            this.Close();
        }

        private void cmd_Start_Click(object sender, EventArgs e)
        {
            try
            {
                if (!(BarCodeReader1.IsOpen))
                    BarCodeReader1.Open();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error opening/writing to serial port :: " + ex.Message, "Error!");
            }
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
            string[] ports = SerialPort.GetPortNames();

            foreach (string port in ports)
            {
                richTextBox1.Text += port + (char)13 + (char)10;
            }
        }

        private void BarCodeReader1_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            string l_Data = BarCodeReader1.ReadExisting();
            textBox1.Text = l_Data;
        }
    }
}

解决步骤 #

• 绑定DataReceived事件
  事件未触发大概率是因为没有完成事件绑定。可以在Form构造函数中添加代码绑定：

  public Form1()
  {
      InitializeComponent();
      // 其他串口参数设置...
      BarCodeReader1.DataReceived += BarCodeReader1_DataReceived;
  }
  

  或者在Visual Studio设计器中，选中BarCodeReader1控件，在属性窗口的事件列表里找到DataReceived，选择对应的处理方法。

• 修复跨线程UI访问问题
  DataReceived事件在后台线程触发，直接修改UI控件会导致线程安全问题，可能静默失败。需要切换到UI线程更新：

  private void BarCodeReader1_DataReceived(object sender, SerialDataReceivedEventArgs e)
  {
      string l_Data = BarCodeReader1.ReadExisting();
      textBox1.Invoke(new Action(() => {
          textBox1.Text = l_Data;
      }));
  }
  

• 核对串口参数与设备匹配
  确认波特率、奇偶校验、数据位、停止位完全匹配设备实际参数。部分条码阅读器会以换行符作为数据结束标记，可尝试设置：

  BarCodeReader1.NewLine = "\r\n";
  // 并将ReadExisting替换为ReadLine
  string l_Data = BarCodeReader1.ReadLine();
  

• 验证串口是否成功打开
  在打开串口后添加确认提示，排除串口未正常打开的情况：

  private void cmd_Start_Click(object sender, EventArgs e)
  {
      try
      {
          if (!(BarCodeReader1.IsOpen))
          {
              BarCodeReader1.Open();
              MessageBox.Show("串口已成功打开");
          }
      }
      catch (Exception ex)
      {
          MessageBox.Show("Error opening/writing to serial port :: " + ex.Message, "Error!");
      }
  }
  

• 移除多余SerialPort实例
  代码中声明的全局SerialPort port实例未被使用，建议移除避免混淆。

内容的提问来源于stack exchange，提问作者Nitin Gandevikar