VB.NET中编写OPC访问WinCC变量时,DataChange事件程序不执行,为什么呢? 我是在Visual Stual 2005中,加入了引用"Siemens OPC DAAutomation 2.0"
Dim WithEvents MyOPCGroup As OPCSiemensDAAutomation.OPCGroup
Private Sub MyOPCGroup_DataChange(ByVal TransactionID As Long, ByVal NumItems As Long, ByVal ClientHandles() As Long, ByVal ItemValues() As Long, ByVal Qualities() As Long, ByVal TimeStamps() As Date)