Imports System
Imports System.IO.Ports

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        '獲取計算機有效串口
        Dim ports As String() = SerialPort.GetPortNames() '必須用命名空間，用SerialPort,獲取計算機的有效串口
        Dim port As String
        For Each port In ports
            portnamebox.Items.Add(port) '向combobox中添加項
        Next port
        '初始化界面
        baudratebox.SelectedIndex() = 2
        portnamebox.SelectedIndex() = 0
        Serial_Port1() '初始化串口
        Label3.Text = SerialPort1.IsOpen
        statuslabel.Text = "串口未連接"
        statuslabel.ForeColor = Color.Red
        sendbox.Text = "123"
        ' baudratebox.Text = baudratebox.Items(0) 注釋和不注釋的地方可以替換
        'portnamebox.Text = portnamebox.Items(0)
    End Sub

    Private Sub Serial_Port1() '設置串口參數(shù)
        SerialPort1.BaudRate = Val(baudratebox.Text) '波特率
        SerialPort1.PortName = portnamebox.Text '串口名稱
        SerialPort1.DataBits = 8 '數(shù)據(jù)位
        SerialPort1.StopBits = IO.Ports.StopBits.One '停止位
        SerialPort1.Parity = IO.Ports.Parity.None '校驗位
    End Sub

    '關閉串口連接
    Private Sub closebtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles closebtn.Click
        Try
            SerialPort1.Close() '關閉串口
            Label3.Text = SerialPort1.IsOpen
            If SerialPort1.IsOpen = False Then
                statuslabel.Text = "串口未連接"
                statuslabel.ForeColor = Color.Red
                receivebox.Text = ""
                receivebytes.Text = ""
            End If
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub

    '打開串口連接
    Private Sub openbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles openbtn.Click
        Try
            SerialPort1.Open() '打開串口
            Label3.Text = SerialPort1.IsOpen
            If SerialPort1.IsOpen = True Then
                statuslabel.Text = "串口已連接"
                statuslabel.ForeColor = Color.Green
            End If
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub


    '發(fā)送數(shù)據(jù)
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Try
            SerialPort1.Write(sendbox.Text)
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try

    End Sub

    '觸發(fā)接收事件
    Public Sub Sp_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        Me.Invoke(New EventHandler(AddressOf Sp_Receiving)) '調(diào)用接收數(shù)據(jù)函數(shù)
    End Sub

    '接收數(shù)據(jù)
    Private Sub Sp_Receiving(ByVal sender As Object, ByVal e As EventArgs)
        Dim strIncoming As String
        Try
            receivebytes.Text = Str(Val(receivebytes.Text) + SerialPort1.BytesToRead)
            If SerialPort1.BytesToRead > 0 Then
                Threading.Thread.Sleep(100) '添加的延時
                strIncoming = SerialPort1.ReadExisting.ToString '讀取緩沖區(qū)中的數(shù)據(jù)
                SerialPort1.DiscardInBuffer()
                receivebox.Text = strIncoming
            End If
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub
End Class