OPC Server示例教程：OPC客户端——VB.NET示例

此示例的代码使用OPC 如果从.NET访问OPC Server，则需要交换COM和.NET的包装器。 自动化包装器（OPCDAAUTO.DLL），因此它几乎等于VB6.0。

OPC Server是一套利用微软的COM/DCOM技术实现工业自动化资料获取的架构。OPC Server提供OPC接口，它将与之相连的物理设备（PLC）的信息值通过接口返回到客户端应用程序。也就是说，客户端通过这些接口，可以获得与OPC Server连接的物理设备的信息。对于集成应用程序，只要支持OPC接口，就能轻易访问物理设备，而无需相关的技术信息。 程序设计者可以使用相同的程序代码，操作不同的硬件装置，充分达成软件复用的目的。

【OPC Server 最新版下载】

它使用OPC Server引入了简单的示例程序。此示例的代码使用OPC 如果从.NET访问OPC Server，则需要交换COM和.NET的包装器。 自动化包装器（OPCDAAUTO.DLL），因此它几乎等于VB6.0。

Declaration

Option ExplicitPublic OpcServer As IOPCServerDispPublic OpcItemMgt As IOPCItemMgtDispPublic OpcItem As IOPCItemDispPrivate Const ItemMax = 8Private Const OPC_DS_CACHE = 1Private Const OPC_DS_DEVICE = 2Dim ClientHandles(ItemMax) As LongDim ServerHandles As VariantDim bConnect As Boolean

连接到OPC服务器，创建OPCGroup和添加标签

Private Sub CONNECT_Click()  On Error GoTo err_hd  Dim i%  If bConnect Then    CONNECT.Caption = "Connect"    Set OpcServer = Nothing    Set OpcItemMgt = Nothing    Set OpcItem = Nothing    bConnect = False    READ_Button.Enabled = False    WRITE_Button.Enabled = False    For i% = ItemName.lbound To ItemName.ubound      ItemName(i%).Enabled = True    Next i%    Exit Sub  End If  '*** Connect to OPC Server ***  Set OpcServer = CreateObject(Form1.ServerName.Text)  If TypeName(OpcServer) = TypeName(Nothing) Then Return  '*** Add OPCGroup ***  Dim UpdateRate As Long  Dim ServerHdl As Long  UpdateRate = UpdateRateSet.Text  Set OpcItemMgt = OpcServer.AddGroup("Group One", True, UpdateRate, 22, 1, 0, ServerHdl, UpdateRate)  If TypeName(OpcItemMgt) = TypeName(Nothing) Then Return  '*** Add OPCItems ***  Dim ItemIDs(ItemMax) As String  Dim AccessPaths(ItemMax) As String  Dim Active(ItemMax) As Boolean  Dim Errors As Variant  Dim ItemObjects As Variant  Dim DataType(ItemMax) As Variant  For i% = 0 To ItemMax - 1    Active(i%) = True    ClientHandles(i%) = 22 + i%    AccessPaths(i%) = ""    ItemIDs(i%) = Form1.ItemName(i%).Text    DataType(i%) = 2  Next i%  OpcItemMgt.AddItems ItemMax, ItemIDs, Active,ClientHandles,            ServerHandles, Errors, ItemObjects, AccessPaths, DataType  Set OpcItem = ItemObjects(0)  bConnect = True  CONNECT.Caption = "DisConnect"  READ_Button.Enabled = True  WRITE_Button.Enabled = True  For i% = ItemName.lbound To ItemName.ubound    ItemName(i%).Enabled = False  Next i%  Exit Suberr_hd:  MsgBox "Error connecting"  For i% = 0 To ItemMax - 1    Form1.Value(i%) = "Error"  Next i%End Sub

缓存读取

Private Sub READ_Button_Click()  Dim ReadValue As Variant  Dim pQuality As Variant  Dim pTimestamp As Variant  Dim Errors As Variant  Dim i%  Dim io As IOPCSyncIODisp  Set io = OpcItemMgt  '*** Cache Read ***  io.OPCRead OPC_DS_CACHE, ItemMax, ServerHandles, ReadValue, pQuality, pTimestamp, Errors  For i% = 0 To ItemMax - 1    Form1.Value(i%) = ReadValue(i%)    pTimestamp(i%) = DateAdd("h", 9, pTimestamp(i%))    Form1.Time(i%) = pTimestamp(i%)    Form1.Quality(i%) = pQuality(i%)  Next i%End Sub

SyncWrite

Private Sub WRITE_Button_Click()  Dim WriteValue(ItemMax) As Variant  Dim io As IOPCSyncIODisp  Dim Errors As Variant  Dim i%  Set io = OpcItemMgt  For i% = 0 To ItemMax - 1    WriteValue(i%) = Form1.Value(i%)  Next i%  '*** SyncWrite ***  io.OPCWrite ItemMax, ServerHandles, WriteValue, ErrorsEnd Sub

标签：OPC工业4.0工业物联网工业设计

来源：慧都