Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO.Ports;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;



namespace SerialPort
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            cmdClose.Enabled = false;
            foreach (String s in System.IO.Ports.SerialPort.GetPortNames()) 
            {
                txtPort.Items.Add(s);
            }
        }

    public System.IO.Ports.SerialPort sport;

    public void serialport_connect(String port, int baudrate , Parity parity, int databits, StopBits stopbits) 
    {
        DateTime dt = DateTime.Now;
        String dtn = dt.ToShortTimeString();

        sport = new System.IO.Ports.SerialPort(
        port, baudrate, parity, databits, stopbits);
        try
        {
            sport.Open();
            cmdClose.Enabled = true;
            cmdConnect.Enabled = false;
            txtReceive.AppendText("[" + dtn + "] " + "Connected\n");
            sport.DataReceived += new SerialDataReceivedEventHandler(sport_DataReceived);
        }
        catch (Exception ex) { MessageBox.Show(ex.ToString(), "Error"); }
    }

    private void sport_DataReceived(object sender, SerialDataReceivedEventArgs e) 
    {
        DateTime dt = DateTime.Now;
        String dtn = dt.ToShortTimeString();
        txtReceive.AppendText("["+dtn+"] "+"Received: "+sport.ReadExisting()+"\n");
    }

    private void cmdConnect_Click(object sender, EventArgs e)
    {
        String port = txtPort.Text;
        int baudrate = Convert.ToInt32(cmbbaudrate.Text);
        Parity parity = (Parity)Enum.Parse(typeof(Parity), cmbparity.Text);
        int databits = Convert.ToInt32(cmbdatabits.Text);
        StopBits stopbits = (StopBits)Enum.Parse(typeof(StopBits), cmbstopbits.Text);

        serialport_connect(port, baudrate, parity, databits, stopbits);

    }

    private void button1_Click(object sender, EventArgs e)
    {
        DateTime dt = DateTime.Now;
        String dtn = dt.ToShortTimeString();
        String data = txtDatatoSend.Text;
        sport.Write(data);
        txtReceive.AppendText("[" + dtn + "] " + "Sent: " + data + "\n");
    }

    private void cmdClose_Click_1(object sender, EventArgs e)
    {
        DateTime dt = DateTime.Now;
        String dtn = dt.ToShortTimeString();

        if (sport.IsOpen) 
        {
            sport.Close();
            cmdClose.Enabled = false;
            cmdConnect.Enabled = true;
            txtReceive.AppendText("[" + dtn + "] " + "Disconnected\n");
        }
    }
}

}

大家好，当我尝试将波特率从9600设置为115200时，我遇到了抛出InvalidOperationException的问题。

知道为什么会这样吗？提前谢谢。

Answer 1

这里发生的是你从非UI线程获得串口回调，并且在回调中你正在尝试更改UI组件。

你不被允许这样做，你会得到你所看到的例外。

最佳解决方案取决于您使用的.Net版本，但无论您使用何种版本，都可以使用Control.BeginInvoke()来解决它。

我提供的链接上有一些示例代码。

请注意，它没有设置导致问题的波特率。这是sport_DataReceived()中的代码，它尝试更新UI组件（您可以从发布的第二个图像中看到）。

您可以按如下方式更改该功能：

private void sport_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    this.BeginInvoke(new Action(() =>
    {
        DateTime dt = DateTime.Now;
        String dtn = dt.ToShortTimeString();
        txtReceive.AppendText("[" + dtn + "] " + "Received: " + sport.ReadExisting() + "\n");
    }));
}

这样做会导致在UI线程上调用上面Action的代码。

InvalidOperationException将波特率设置为9600到115200

1 个答案: