Public Class Form1

    '監視処理の開始 

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Me.BackgroundWorker1.WorkerSupportsCancellation = True

        Me.BackgroundWorker1.RunWorkerAsync()

    End Sub



    '非常停止ボタン 

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        Me.BackgroundWorker1.CancelAsync()

    End Sub



    Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork

        While True

            If Me.BackgroundWorker1.CancellationPending = True Then

                e.Cancel = True

                Exit While

            End If

            '監視処理など 

        End While

    End Sub



    Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As System.Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted

        If e.Cancelled = True Then

            MsgBox("非常停止")

        End If

    End Sub

End Class