提供一个VB.NET与OMRON以太网通讯的代码，是我项目里面复制出来的：
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Dim Handle1 As Int32 'PLC的连接句柄
Dim EntLink As Boolean '连接标志
Dim PLC As New FinsTcp.PlcClient '引用OMRON的通讯组件
Private Sub butLink_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butLink.Click
Dim re As Short
Dim restr As String = ""
re = PLC.EntLink(Trim(txtLocalIP.Text), Val(txtLocalPort.Text), Trim(txtRemoteIP.Text), Val(txtRemotePort.Text), "DEMO", Handle1)
txtReLink.Text = re.ToString
If re = 0 Then
EntLink = True
MsgBox("PLC联接成功! ")
Else
EntLink = False
MsgBox("PLC联接失败: " restr)
End If
End Sub
Private Sub butClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butClose.Click
Dim re As Short
EntLink = False
re = PLC.DeLink(Handle1)
txtReClose.Text = re.ToString
End Sub
Private Sub butRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butRead.Click
Dim re As Short
Dim i As Short
Dim RD() As Object
ReDim RD(Val(txtReadCnt.Text - 1))
If Not EntLink Then
MsgBox("还未与PLC建立联接！")
Exit Sub
End If
Dim mry As FinsTcp.PlcClient.PlcMemory = cmbReadMry.SelectedIndex + 1
Dim typ As FinsTcp.PlcClient.DataType = cmbReadType.SelectedIndex + 1
re = PLC.CmdRead(Handle1, mry, typ, CUShort(Val(txtReadAdd.Text)), CUShort(Val(txtReadCnt.Text)), RD)
txtReRead.Text = re.ToString
lstRead.Items.Clear()
For i = 0 To UBound(RD) Step 1
If Not IsNothing(RD(i)) Then lstRead.Items.Add(RD(i))
Next i
If re 0 Then
Timer1.Enabled = False
butScan.Text = "Cycle R/W"
End If
End Sub
Private Sub butWrite_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butWrite.Click
Dim re As Short
Dim i As Short
Dim temp() As String
Dim WD() As Object
If Not EntLink Then
MsgBox("还未与PLC建立联接！")
Exit Sub
End If
ReDim WD(Val(txtWriteCnt.Text) - 1)
temp = Split(txtWrite.Text, vbCrLf)
For i = 0 To UBound(WD) Step 1
If i UBound(temp) Then
WD(i) = 0
Else
WD(i) = Trim(temp(i))
End If
Next i
Dim mry As FinsTcp.PlcClient.PlcMemory = cmbWriteMry.SelectedIndex + 1
Dim typ As FinsTcp.PlcClient.DataType = cmbWriteType.SelectedIndex + 1
re = PLC.CmdWrite(Handle1, mry, typ, CUShort(Val(txtWriteAdd.Text)), CUShort(Val(txtWriteCnt.Text)), WD)
txtReWrite.Text = re.ToString
If re 0 Then
Timer1.Enabled = False
butScan.Text = "Cycle R/W"
End If
End Sub
没用过modbus通信写过，但是使用自由通信可以
VB.net带有通信控件，在里面设置波特率、奇偶效验、数据位、COM口
在PLC里做个自由通信就可以
用 vb.net socket通信
Dim th As Threading.Thread
2 Dim tcpl As System.Net.Sockets.TcpListener
3
4 Private Sub Form1_Load()Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
5 th = New System.Threading.Thread(New System.Threading.ThreadStart(AddressOf MyListen))
6 th.Start()
7 End Sub
8
9 Public Sub SendMessage()Sub SendMessage(ByVal IP As String, ByVal SendMsg As String)
10 Try
11 If IP "" Then
12 Dim tcpc As New System.Net.Sockets.TcpClient(IP, 5656)
13 Dim tcpStream As Net.Sockets.NetworkStream = tcpc.GetStream
14 Dim reqStream As New IO.StreamWriter(tcpStream)
15 reqStream.Write(SendMsg)
16 reqStream.Flush()
17 tcpStream.Close()
18 tcpc.Close()
19 End If
20 Catch ex As Exception
21 MsgBox(ex.Message.ToString)
22 End Try
23 End Sub
24 Private Sub MyListen()Sub MyListen()
25 Try
26 Dim ipAddress As System.Net.IPAddress = System.Net.Dns.Resolve(System.Net.Dns.GetHostName).AddressList(0)
27 tcpl = New System.Net.Sockets.TcpListener(ipAddress, 5656)
28 tcpl.Start()
29 While True
30 Dim s As System.Net.Sockets.Socket = tcpl.AcceptSocket()
31 Dim MyBuffer(1024) As Byte
32 Dim i As Integer
33 i = s.Receive(MyBuffer)
34 If i 0 Then
35 Dim lstrRec As String
36 Dim j As Integer
37 For j = 0 To i - 1
38 TextBox1.Text += Chr(MyBuffer(j)) ","
39 Next
40 End If
41 End While
42 Catch ex As Exception
43 MsgBox(ex.Message.ToString)
44 End Try
45 End Sub
46
47 Private Sub Button1_Click()Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
48 SendMessage("192.168.0.61", TextBox2.Text)
49 End Sub