跨线程访问vb.net中的串行端口问题 [英] Cross thread Problem in accessing serial port in vb.net

问题描述

你好，
我正在为某种硬件开发应用程序，其中我想通过串行端口从硬件设备接收数据，并将此数据存储在变量中并在文本框中显示.
但是当我尝试在文本框中显示时，它给出了线程交叉检测的错误.
跨线程操作无效:控制TextBox1是从创建该线程的线程之外的线程访问的"

Hello,
I am developing an application for some kind of hardware in which i want to receive data from hardware device through serial port and store this data in a variable and display it in textbox.
but when i try to display in text box then it gives an error of Thread Cross detection.
"Cross-thread operation not valid: Control TextBox1 accessed from a thread other than the thread it was created on"

Imports System.Data.OleDb
Imports System.IO.Ports

Public Class Student_Entry
    Dim str12 As String
    Dim cn As OleDbConnection
    Dim cmd As OleDbCommand
    Dim dr As OleDbDataReader
    Dim da As OleDbDataAdapter
    Dim str As String
    Dim icount As Integer
    Dim rcount As Integer
    Dim data As DataTable
    Dim response As String, deviceadd As String
    Dim c As Integer, i As Integer
    Dim datareceive As String
    Dim deviceNum As Integer, devicetemp As Integer
 Private Sub Student_Entry_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Try
            For Each sp As String In SerialPort.GetPortNames
                portcode = sp.ToString()
            Next
            With SerialPort1
                .PortName = portcode
                .BaudRate = 115200
                .Parity = IO.Ports.Parity.None
                .DataBits = 8
                .StopBits = IO.Ports.StopBits.Two
                .Open()
            End With
        Catch ex As Exception
            MsgBox("Please Change Port setting")
        End Try
    End Sub
''Receiving data from serial port when device active
Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        On Error Resume Next
        With SerialPort1
            response = ""
            datareceive = SerialPort1.ReadExisting()
            For i As Integer = 1 To Len(datareceive)
                c = Asc(Mid(datareceive, i, 2))
                response = response & Hex(c) & " "
            Next
            If Mid(response, 1, 2) = "7B" And Mid(response, 31, 2) = "7D" And Len(response) = 33 Then
                deviceadd = Mid(response, 14, 11)
                MsgBox(deviceadd)   ''This msg box working properly 
                TextBox1.Text = deviceadd  ''But the value of deviceadd is not display in TextBox1 it generates cross thread detection problem
                deviceNum = Mid(response, 23, 1)
                devicetemp = Mid(response, 1, 23)
                ''ans = Mid(response, 25, 1)
               
            End If
        End With
    End Sub

请给我适当的解决方案，以解决此问题
谢谢哥们...

Please Give me proper solution for this problem
Thanks buddy...

推荐答案

好确定最后我已经解决了这个问题，我想和我的朋友们分享一下...
我已经清楚地添加了此功能....
首先，我检查是否有任何跨线程情况发生，然后我将其修复

Ok Ok Finally I had got solution for this problem and i would like to share it with my friends.....
I have added this function working clearly....
First I check there is any cross thread condition occur if yes then i fix it

Imports System.Data.OleDb
Imports System.IO.Ports
 
Public Class Student_Entry
    Dim str12 As String
    Dim cn As OleDbConnection
    Dim cmd As OleDbCommand
    Dim dr As OleDbDataReader
    Dim da As OleDbDataAdapter
    Dim str As String
    Dim icount As Integer
    Dim rcount As Integer
    Dim data As DataTable
    Dim response As String, deviceadd As String
    Dim c As Integer, i As Integer
    Dim datareceive As String
    Dim deviceNum As Integer, devicetemp As Integer
 Private Sub Student_Entry_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Try
            For Each sp As String In SerialPort.GetPortNames
                portcode = sp.ToString()
            Next
            With SerialPort1
                .PortName = portcode
                .BaudRate = 115200
                .Parity = IO.Ports.Parity.None
                .DataBits = 8
                .StopBits = IO.Ports.StopBits.Two
                .Open()
            End With
        Catch ex As Exception
            MsgBox("Please Change Port setting")
        End Try
    End Sub
''Receiving data from serial port when device active
Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        On Error Resume Next
        With SerialPort1
            response = ""
            datareceive = SerialPort1.ReadExisting()
            For i As Integer = 1 To Len(datareceive)
                c = Asc(Mid(datareceive, i, 2))
                response = response & Hex(c) & " "
            Next
            If Mid(response, 1, 2) = "7B" And Mid(response, 31, 2) = "7D" And Len(response) = 33 Then
                deviceadd = Mid(response, 14, 11)
                MsgBox(deviceadd)   ''This msg box working properly
                ''Instead of below step we calling a method 
               '' TextBox1.Text = deviceadd  
                call chekthread()               
            End If
        End With
    End Sub

''Check Thread cross 
Private Sub chekthread()
        Try
         If (TextBox1.InvokeRequired) Then
               
                TextBox1.Invoke(New MethodInvoker(AddressOf chekthread), New Object() {Text})
                
            End If
            TextBox1.Text = deviceadd.ToString()

多亏了我的自我

Thanks to my self

，或者在4.0中，您可以像这样调用文本框:

Or in 4.0 you can call the textbox like this:

'Receiving data from serial port when device active
Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        On Error Resume Next
        With SerialPort1
            response = ""
            datareceive = SerialPort1.ReadExisting()
            For i As Integer = 1 To Len(datareceive)
                c = Asc(Mid(datareceive, i, 2))
                response = response & Hex(c) & " "
            Next
            If Mid(response, 1, 2) = "7B" And Mid(response, 31, 2) = "7D" And Len(response) = 33 Then
                deviceadd = Mid(response, 14, 11)
                MsgBox(deviceadd)   
        
               Me.Invoke(Sub()
                   TextBox1.Text = deviceadd
                         End Sub)
            End If
        End With
    End Sub

您不能直接访问UI控件来自创建线程之外的线程.为此，您必须使用 IsInvokeRequired InvokeRequired属性和Invoke()方法. Google用这些术语来查找更多信息.

You cannot directly access a UI control from threads other than the one that created it. To do so, you have to use the IsInvokeRequired InvokeRequired property and the Invoke() method. Google these terms to find out more.

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