Option Explicit Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long Private Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal X As Long, ByVal Y As Long) As Long Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hdc As Long) As Long Private Type POINTAPI X As Long Y As Long End Type Dim dc As Long Dim p As POINTAPI Public data As String Sub Form_Load() Timer1.Interval = 200 Timer1.Enabled = True MSComm1.CommPort = 1 MSComm1.Settings = "9600,E,7,1" '设置串口参数 MSComm1.InputMode = comInputModeText MSComm1.InBufferSize = 1024 MSComm1.PortOpen = True End Sub Private Sub Timer1_Timer() GetColorUnderCursor GetColorUndersCursor Dim receiveData As String AutoRedraw = True receiveData = MSComm1.Input Text1 = receiveData '打印PLC返回的数据 'MSComm1.PortOpen = False End Sub Private Sub GetColorUnderCursor() GetCursorPos p Cls AutoRedraw = True dc = GetDC(0) Print GetPixel(dc, p.X, p.Y) ReleaseDC 0, dc End Sub Private Sub GetColorUndersCursor() GetCursorPos p dc = GetDC(0) Dim color As Long color = GetPixel(dc, p.X, p.Y) ReleaseDC 0, dc Dim data As String If color = 11250603 Then data = Chr(2) & "110C8020200" & Chr(3) & "34" Text2.Text = data MSComm1.Output = data End If End Sub mscomm1与PLC通信协议为RS-232c，要求修改代码，让plc返回值为十六进制

可以将返回的值转换为十六进制格式，代码如下所示：

Option Explicit

Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal X As Long, ByVal Y As Long) As Long
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hdc As Long) As Long

Private Type POINTAPI
    X As Long
    Y As Long
End Type

Dim dc As Long
Dim p As POINTAPI
Public data As String

Sub Form_Load()
    Timer1.Interval = 200
    Timer1.Enabled = True
    MSComm1.CommPort = 1
    MSComm1.Settings = "9600,E,7,1" '设置串口参数
    MSComm1.InputMode = comInputModeText
    MSComm1.InBufferSize = 1024
    MSComm1.PortOpen = True
End Sub

Private Sub Timer1_Timer()
    GetColorUnderCursor
    GetColorUndersCursor
    Dim receiveData As String
    AutoRedraw = True
    receiveData = MSComm1.Input
    Text1 = receiveData '打印PLC返回的数据
    'MSComm1.PortOpen = False
End Sub

Private Sub GetColorUnderCursor()
    GetCursorPos p
    Cls
    AutoRedraw = True
    dc = GetDC(0)
    Print GetPixel(dc, p.X, p.Y)
    ReleaseDC 0, dc
End Sub

Private Sub GetColorUndersCursor()
    GetCursorPos p
    dc = GetDC(0)
    Dim color As Long
    color = GetPixel(dc, p.X, p.Y)
    ReleaseDC 0, dc
    Dim data As String
    If color = 11250603 Then
        data = Chr(2) & "110C8020200" & Chr(3) & "34"
        Text2.Text = data
        MSComm1.Output = data
        Dim receiveData As String
        receiveData = MSComm1.Input
        If receiveData <> "" Then
            Dim hexData As String
            Dim i As Integer
            For i = 1 To Len(receiveData)
                hexData = hexData & Hex(Asc(Mid(receiveData, i, 1)))
            Next i
            Text1.Text = hexData
        End If
    End If
End Sub

在GetColorUndersCursor子程序中，添加了转换为十六进制的代码。当PLC返回数据时，会将数据转换为十六进制格式，然后在Text1中显示。