I did more careful timings. The single lineCComVariant vResults(EasyDAClientPtr->ReadMultipleItems(machine.c_str(), server.c_str(), CComVariant(LPSAFEARRAY(*ItemInArray)), vMissing));takes about 1.5 seconds each subsequent time. The following code takes another 2.5 seconds each timefor(i = ResultArray.GetLowerBound(0); i < ResultArray.GetUpperBound(0); ++i){ IDAVtqResultPtr DAVtqResultPtr(ResultArray); if(DAVtqResultPtr->Exception == NULL) { IDAVtqPtr DAVtqPtr(DAVtqResultPtr->Vtq); value = (float) DAVtqPtr->Value.dblVal; } else { ICOMExceptionPtr COMExceptionPtr = DAVtqResultPtr->Exception; _tprintf(_T("%d: failure: %s\n"), i, COLE2T(COMExceptionPtr->Message)); }}so it seems that the actual reading time concurs with yours given that my network adds some overhead. However getting the result out of the data structure is expensive. Am I doing something wrong? I should note that the number of exceptions is low, so that the part in the else clause does not matter much.The OPC Server that I'm connecting to is part of a package called RecordData, which is an internal developement of a power provider in Germany, so it is not a standard commercial OPC server. I will try to do it with subscriptions and see how far I get.

Thank you for your helpful suggestions.Ad 1. I made those changes and it did not improve. The times are the same as before. The very first time that I start my program, the first read loop takes about 16 seconds, after that the loop takes about 4 seconds. However when I then start my program a second time, even the first loop execution takes about 4 seconds and then remains at that level ...Ad 2. Using your method, I retrieved an error. It occurs particularly with 2 of my over 1000 items and says: "Topic not updated for the first time (timeout)."Ad 3. Using your example, the writing operation now writes. Thank you.With regard to the timing problem, could it be related to having to instantiate various object on every execution of the loop, e.g. the IEasyDAClientPtr or the CComSafeArray ResultArray among several others?

Hi there,I am new to both DCOM, OPC and QuickOPC development ... so I apologize in advance for trivialities. My task is to read several values from an OPC server, to do some processing and to write some values back to the same server. This loop is repeated every few seconds essentially forever.For development I am using C++ in VS2005, so I started with the example called Examples\CPP\VS2008\Win32\ReadMultipleItems. After some initial troubles, I can compile and run this and it works. However, I'm having three issues at a second look ...1. I looped the code in that example's main function to read 1027 items each time. It takes 4.2 seconds to execute on each loop. The OPC server is on another machine but the network is fast. Is this normal? What can I do to hurry this up? I would like to do it in under 1 second. One point may be to declare the various members somewhere outside but I am not familiar enough with DCOM to do this and have it still work ... help?2. The function "->Vtq" on line 37 of that example rarely but sometimes fails returning an exception in debug mode. No text is output just a FAILED macro returns an opc_issue exception ... what can I do? How can these errors be caught and nicely dealt with?3. I attempted to rewrite the same example to do writing ... I failed. Basically, I have an array of doubles that I have to write out. The conversion of that to VARIANT and so on is something that I probably messed up. I'm trying to use the function ReadMultipleItemValues and this crashes. Can someone show how to convert an array of doubles to the right VARIANT array that will work with this function.Basically what I am looking for is the ReadMultipleItems example broken into two bits - initialization of everything and the core suitable for looping - and then also extended for writing an array of values and possibly for error checking.Btw, the OPCserver I have to link to does not support subscribing to values, so I really must poll them all on every loop ...Thank you very much!