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 p As POINTAPI Dim dc As Long Sub Form_Load() Timer1.Interval = 200 Timer1.Enabled = True MSComm1.CommPort = 1 MSComm1.Settings = "9600,E,7,1" MSComm1.InputMode = comInputModeText MSComm1.InBufferSize = 1024 MSComm1.PortOpen = True End Sub Private Sub Timer1_Timer() GetColorUnderCursor SendData End Sub Private Sub GetColorUnderCursor() GetCursorPos p dc = GetDC(0) Dim color As Long color = GetPixel(dc, p.X, p.Y) ReleaseDC 0, dc Text3.Text = color End Sub Private Sub SendData() GetCursorPos p dc = GetDC(0) Dim color As Long color = GetPixel(dc, p.X, p.Y) ReleaseDC 0, dc If color = 8421504 Then Dim data As String 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优化代码，要求PLC的返回值和数据输出能够及时更新，

为了优化代码，可以考虑将获取颜色和发送数据的逻辑合并到一起，避免重复代码。同时，可以在发送数据之后立即读取PLC的返回值，以保证数据输出能够及时更新。

以下是优化后的代码：

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 p As POINTAPI
Dim dc As Long

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

Private Sub Timer1_Timer()
    SendData
End Sub

Private Sub SendData()
    GetCursorPos p
    dc = GetDC(0)
    Dim color As Long
    color = GetPixel(dc, p.X, p.Y)
    ReleaseDC 0, dc
    
    If color = 8421504 Then
        Dim data As String
        data = Chr(2) & "110C8020200" & Chr(3) & "34"
        Text2.Text = data
        MSComm1.Output = data
        
        Do While MSComm1.InBufferCount = 0
            DoEvents
        Loop
        
        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
        
        Text3.Text = color
    End If
End Sub

这样，每次定时器触发时，会先获取颜色，如果符合条件则发送数据并立即读取PLC的返回值，然后更新数据输出。同时，由于颜色获取和发送数据的逻辑合并到一起，代码也更加简洁。