【正文】
圖三,OPC與WinCC通訊測(cè)試測(cè)試運(yùn)行結(jié)果如圖三。 程序運(yùn)行通過Private Sub Text8_Change(Index As Integer)函數(shù),當(dāng)串口讀取了值有變化時(shí),在WinCC組態(tài)界面中實(shí)際值I/O域中,就可以看到其實(shí)際值了(Tag(1))。如下:Private Sub Command2_Click()On Error Resume Next 釋放組和服務(wù)器對(duì)象 與服務(wù)器斷開連接并且清除 Set MyOPCItemColl = NothingSet MyOPCGroup = NothingSet MyOPCGroupColl = NothingSet MyOPCServer = Nothing = False 連接成功標(biāo)志End Sub至此,用VB 。 OPC客戶端連接后要占用服務(wù)器資源,所以如果不需要使用OPC時(shí),必須進(jìn)行OPC連接斷開。讀取Private Sub MyOPCGroup_DataChange(ByVal TransactionID As Long, ByVal NumItems As Long, ClientHandles() As Long, ItemValues() As Variant, Qualities() As Long, TimeStamps() As Date)Dim ii As LongFor ii = 1 To 4ItemIDsValue(ClientHandles(ii)) = ItemValues(ii) 對(duì)改變的值讀入本數(shù)組Text5(ClientHandles(ii)).Text = ItemIDsValue(ClientHandles(ii))Next iiEnd Sub寫入Private Su