form1.frm

modbus tcp/ip 实例,实现PC与3个PLC之间利用MODBUS作为应用层,TCP/IP作为传输层.

VERSION 5.00
Object = "{248DD890-BB45-11CF-9ABC-0080C7E7B78D}#1.0#0"; "MSWINSCK.OCX"
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   3090
   ClientLeft      =   60
   ClientTop       =   450
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   3090
   ScaleWidth      =   4680
   StartUpPosition =   3  '窗口缺省
   Begin VB.CommandButton readbutton 
      Caption         =   "Command1"
      Height          =   495
      Left            =   1440
      TabIndex        =   1
      Top             =   1800
      Width           =   1215
   End
   Begin VB.CommandButton connectbutton 
      Caption         =   "Command1"
      Height          =   495
      Left            =   2640
      TabIndex        =   0
      Top             =   840
      Width           =   975
   End
   Begin MSWinsockLib.Winsock Winsock 
      Left            =   960
      Top             =   840
      _ExtentX        =   741
      _ExtentY        =   741
      _Version        =   393216
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Form_Load()
  aflag = True
  bflag = True
  outbuf(0) = &H0
  outbuf(1) = &H0
  outbuf(2) = &H0
  outbuf(3) = &H0
  outbuf(4) = &H0
  outbuf(5) = &H6
  outbuf(6) = &H0
  outbuf(7) = &H1 'Op-Code
  outbuf(8) = &H0 'Start-Hi
  outbuf(9) = &H0 'Start-Lo
  outbuf(10) = &H0 'Count-Hi
  outbuf(11) = &H1 'Count-Lo
End Sub
'(2) 连接PLC
Private Sub connectbutton_Click()
    Winsock.Close
    Winsock.LocalPort = 0
    Winsock.Connect
End Sub
'(3) 发送数据
Private Sub readbutton_Click()
  Winsock.SendData outbuf
End Sub
'(4) 提取数据
Private Sub Winsock_DataArrival(ByVal bytesTotal As Long)
  Dim inBuf(20) As Byte
  For i = 0 To bytesTotal - 1
     Winsock.GetData inBuf(i)
  Next
  If coil.Value = True Then
    Value.Caption = Str(inBuf(9))
'  //  提取0xxxxx中的数据
  Else
   Value.Caption = Str(inBuf(9) * 256 + inBuf(10))    '提取4xxxxx中的数据
  bflag = Not bflag
  n = n + 1
  Winsock.Close
   Winsock.LocalPort = 0
   Winsock.Connect
End If
'(5) 连续发送
Private Sub Winsock_Connect()
  Do While (n <= step And ((aflag Xor bflag) = True))
    Winsock.SendData outbuf
    aflag = bflag
  Loop
  If n > step Then
    status.Caption = “命令执行完毕，仍保持连接状态”
  End If
End Sub