AI rành vb6 chỉ giúp em xem sai ở đâu với.

[villiers]

Dim textout, textin As String

Private Sub cmdcom_Click()
If cmdcom.Caption = "CONNECTOR" Then
    com1.CommPort = Val(cmbsel.ListIndex + 1)
    com1.PortOpen = True
    cmdsend.Visible = True
    Timer1.Enabled = True
    cmdcom.Caption = "DECONNECT"
Else
    If cmdcom.Caption = "DECONNECT" Then
    Timer1.Enabled = False
    cmdsend.Visible = False
    com1.PortOpen = False
    cmdcom.Caption = "CONNECTOR"
    End If
End If
End Sub

Private Sub cmdsend_Click()
textout = textsend.Text
com1.Output = textout
End Sub


Private Sub Timer1_Timer()
    textin = com1.Input
    If textin <> "" Then
    lbstar.Caption = textin
    End If

End Sub