// This example shows how to subscribe to changes of multiple items and display the value of the item with each change. // SubscribeMultipleItems.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <atlcom.h> #include <atlsafe.h> #include <comutil.h> #import "libid:FAB7A1E3-3B79-4292-9C3A-DF39A6F65EC1" version(5.2) // EasyOpcLib using namespace EasyOpcLib; #define DISPID_EASYDACLIENTEVENTS_ITEMCHANGED 1002 // class CSubscribeMultipleItemsModule : public ATL::CAtlModuleT< CSubscribeMultipleItemsModule > { }; CSubscribeMultipleItemsModule _AtlModule; // CCoEasyDAClientEvents class CCoEasyDAClientEvents : public CComObjectRoot, public IDispEventImpl<1, CCoEasyDAClientEvents, &__uuidof(DEasyDAClientEvents), &__uuidof(__EasyOpcLib), 5, 2> { BEGIN_COM_MAP(CCoEasyDAClientEvents) COM_INTERFACE_ENTRY_IID(__uuidof(IDispatch), CCoEasyDAClientEvents) COM_INTERFACE_ENTRY_IID(__uuidof(DEasyDAClientEvents), CCoEasyDAClientEvents) END_COM_MAP() BEGIN_SINK_MAP(CCoEasyDAClientEvents) // Event handlers must have the __stdcall calling convention SINK_ENTRY_EX(1, __uuidof(DEasyDAClientEvents), DISPID_EASYDACLIENTEVENTS_ITEMCHANGED, &CCoEasyDAClientEvents::ItemChanged) END_SINK_MAP() public: // The handler for EasyDAClient.ItemChanged event STDMETHOD(ItemChanged)(VARIANT varSender, VARIANT varEventArgs) { // Obtain the event arguments IEasyDAItemChangedEventArgsPtr EasyDAItemChangedEventArgsPtr(varEventArgs); IDAItemDescriptorPtr DAItemDescriptorPtr(EasyDAItemChangedEventArgsPtr->ItemDescriptor); IDAVtqPtr VtqPtr(EasyDAItemChangedEventArgsPtr->Vtq); // Not shown in this example: You should test the VtqPtr against NULL. _tprintf(_T("%s: %s\n"), COLE2CT(_bstr_t(DAItemDescriptorPtr->ItemId)), COLE2CT(_bstr_t(VtqPtr->ToString()))); return S_OK; } }; // int _tmain(int argc, _TCHAR* argv[]) { // Initialize the COM library CoInitializeEx(NULL, COINIT_MULTITHREADED); // Instatiate the EasyOPC-DA client object IEasyDAClientPtr EasyDAClientPtr(__uuidof(EasyDAClient)); // Hook the event handler IConnectionPointContainerPtr ConnectionPointContainerPtr(EasyDAClientPtr); IConnectionPointPtr ConnectionPointPtr; ConnectionPointContainerPtr->FindConnectionPoint(__uuidof(DEasyDAClientEvents), &ConnectionPointPtr); CComObject<CCoEasyDAClientEvents>* pCoEasyDAClientEvents = NULL; CComObject<CCoEasyDAClientEvents>::CreateInstance(&pCoEasyDAClientEvents); DEasyDAClientEventsPtr EasyDAClientEventsPtr(pCoEasyDAClientEvents); DWORD Cookie; ConnectionPointPtr->Advise(EasyDAClientEventsPtr, &Cookie); // Create array of OPC item IDs CComSafeArray<BSTR> ItemIdArray(4); ItemIdArray[0] = _T("Simulation.Random"); ItemIdArray[1] = _T("Trends.Ramp (1 min)"); ItemIdArray[2] = _T("Trends.Sine (1 min)"); ItemIdArray[3] = _T("Simulation.Register_I4"); CComVariant vResults(EasyDAClientPtr->SubscribeMultipleItems( /*varMachineNames:*/ _T(""), /*varServerClasses:*/ _T("OPCLabs.KitServer.2"), /*varItemIds:*/ CComVariant(ItemIdArray.Detach()), /*varRequestedUpdateRates:*/ 1000)); CComSafeArray<VARIANT> ResultArray(vResults.parray); for (int i = ResultArray.GetLowerBound(0); i <= ResultArray.GetUpperBound(0); i++) { IHandleResultPtr HandleResultPtr(ResultArray[i]); // Not shown in this example: Obtain the handle of the subscribed item from HandleResultPtr. // The handle is needed if you later wish to unsubscribe from certain items individually. } _tprintf(_T("Processing item changed events for 1 minute...")); Sleep(60*1000); // Unsubscribe from changes to all OPC items EasyDAClientPtr->UnsubscribeAllItems(); // Release all interface pointers BEFORE calling CoUninitialize() ResultArray.Destroy(); vResults.Clear(); EasyDAClientEventsPtr = NULL; ConnectionPointPtr = NULL; ConnectionPointContainerPtr = NULL; EasyDAClientPtr = NULL; CoUninitialize(); return 0; }