前に書いたシリアルポートのデータ表示。
もっと簡単な方法があった。

SerialPortのBytesToReadをBackgroundWorkerのDoWork内でポーリング。
表示させたいときはReportProgressで元スレッドにデータを渡せばいい。
DataReceived？なにそれおいしいの？

Public Class Form1
    Private WithEvents BackgroundWorker1 As New System.ComponentModel.BackgroundWorker
    Private SerialPort1 As New System.IO.Ports.SerialPort

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _
                                                                   Handles MyBase.Load
        If SerialPort1.IsOpen = False Then
            SerialPort1.PortName = System.IO.Ports.SerialPort.GetPortNames()(0)
            SerialPort1.BaudRate = 9600
            SerialPort1.DataBits = 8
            SerialPort1.Parity = System.IO.Ports.Parity.None
            SerialPort1.StopBits = System.IO.Ports.StopBits.One
            SerialPort1.Open()
        End If
        BackgroundWorker1.WorkerReportsProgress = True
        BackgroundWorker1.RunWorkerAsync()
    End Sub

    Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, _
                                         ByVal e As System.ComponentModel.DoWorkEventArgs) _
                                        Handles BackgroundWorker1.DoWork
        Try
            Static rxcnt As Integer = 0
            Static rxbuf(1024) As Byte
            While True
                If SerialPort1.BytesToRead <> 0 Then
                    rxcnt = SerialPort1.Read(rxbuf, rxcnt, SerialPort1.BytesToRead)
                    BackgroundWorker1.ReportProgress(0, rxbuf)
                End If
            End While
        Catch ex As Exception
        End Try
    End Sub

    Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As System.Object, _
                       ByVal e As System.ComponentModel.ProgressChangedEventArgs) _
                                          Handles BackgroundWorker1.ProgressChanged
        Dim rxbuf() As Byte = e.UserState
        TextBox1.Text = rxbuf(0)
    End Sub
End Class

動くんじゃないかな？試してないけど。

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