Keil C51实现单片机与PC usb通讯（上位机）vb如何编写

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
'获取计算机有效串口
Dim ports As String() = SerialPort.GetPortNames() '必须用命名空间，用SerialPort,获取计算机的有效串口
Dim port As String
For Each port In ports
portnamebox.Items.Add(port) '向combobox中添加项
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 = "串口未连接"
statuslabel.ForeColor = Color.Red
sendbox.Text = "123"
' baudratebox.Text = baudratebox.Items(0) 注释和不注释的地方可以替换
'portnamebox.Text = portnamebox.Items(0)
End Sub

Private Sub Serial_Port1() '设置串口参数
SerialPort1.BaudRate = Val(baudratebox.Text) '波特率
SerialPort1.PortName = portnamebox.Text '串口名称
SerialPort1.DataBits = 8 '数据位
SerialPort1.StopBits = IO.Ports.StopBits.One '停止位
SerialPort1.Parity = IO.Ports.Parity.None '校验位
End Sub

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

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

'发送数据
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

'触发接收事件
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)) '调用接收数据函数
End Sub

'接收数据
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) '添加的延时
strIncoming = SerialPort1.ReadExisting.ToString '读取缓冲区中的数据
SerialPort1.DiscardInBuffer()
receivebox.Text = strIncoming
End If
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
End Class

串口通讯的，编程环境， vb.net本回答被提问者采纳