OPCクライアント－VB.NETサンプル

OPCサーバを用いた最も簡単なサンプルプログラムを紹介します。
.NET系の開発言語からOPCサーバーにアクセスするには、COMと.NETの変換を行うラッパーが必要になります。
このサンプルは、OPCオートメーションラッパー（OPCDAAUTO.DLL）を使用していますので、VB6.0とほぼ同じコードになります。




宣言
Option Explicit Public OpcServer As IOPCServerDisp Public OpcItemMgt As IOPCItemMgtDisp Public OpcItem As IOPCItemDisp Private Const ItemMax = 8 Private Const OPC_DS_CACHE = 1 Private Const OPC_DS_DEVICE = 2 Dim ClientHandles(ItemMax) As Long Dim ServerHandles As Variant Dim bConnect As Boolean

OPCサーバーへの接続、グループ登録、アイテム登録
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 '*** OPCサーバー接続 *** Set OpcServer = CreateObject(Form1.ServerName.Text) If TypeName(OpcServer) = TypeName(Nothing) Then Return '*** OPCグループ登録 *** 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 '*** アイテム登録 *** 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 Sub err_hd: MsgBox "Error connecting" For i% = 0 To ItemMax - 1 Form1.Value(i%) = "Error" Next i% End Sub

OPCサーバーからキャッシュ読出
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 '*** 読出実行 *** 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

OPCサーバーへ同期書込
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% '*** 書込実行 *** io.OPCWrite ItemMax, ServerHandles, WriteValue, Errors End Sub

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