Public Class Form1
Dim mSTR As String
Dim strData As String
Dim strDat As String
'Dim mSize1 As Integer
Dim mRecvByte() As Byte
Dim Hexsj As String
Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
Dim mSize As Integer = Me.SerialPort1.BytesToRead
'mSize1 = mSize
ReDim mRecvByte(mSize - 1)
SerialPort1.Read(mRecvByte, 0, mSize)
'mSTR = Encoding.Default.GetString(mRecvByte, 0, mSize)
BeginInvoke(New EventHandler(AddressOf ONMLoadA), SerialPort1.BytesToRead()) '使用委托方式显示接收到的字符串
End Sub
Sub ONMLoadA(ByVal sender As System.Object, ByVal e As System.EventArgs) '委托
'TextBox4.Text = mSTR
Dim i As Integer
For i = 0 To UBound(mRecvByte) 'mSize - 1
strData = strData & IIf(mRecvByte(i) > 15, Hex(mRecvByte(i)), "0" & Hex(mRecvByte(i)))
Next
Dim sj As Byte
For i = 1 To Len(strData) Step 2 '处理为ASCII字符
sj = Val("&H" & Mid(strData, i, 2))
If sj < 32 Or sj > 128 Then '当接收字节中有Chr(0)时，其后字符被切割
strDat = strDat & "."
Else
strDat = strDat & Chr(sj)
End If
Next
TextBox1.Text = strDat '显示字符
TextBox2.Text = strData '显示为16进制
TextBox3.Text = Len(strData) / 2
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
SerialPort1.BaudRate = 9600 '波特率设为
SerialPort1.PortName = "com1" '端口为串口
SerialPort1.ReceivedBytesThreshold = 1
If SerialPort1.IsOpen = False Then SerialPort1.Open() '打开串口
Hexsj = "002702013524200239892700020020010201E9030D07"
TxtSend.Text = Hexsj
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
strData = ""
strDat = ""
TextBox1.Text = ""
TextBox2.Text = ""
TextBox3.Text = ""
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim bytHex() As Byte
ReDim bytHex((Len(Hexsj) \ 2) - 1)
Dim i As Integer
For i = 1 To Len(Hexsj) Step 2
bytHex((i - 1) / 2) = Val("&H" & Mid(Hexsj, i, 2))
Next
SerialPort1.Write(bytHex, 0, bytHex.Length)
End Sub
End Class