My apologies. I am not sure what you want me to do. Can you supply the statement to "print out the HResult and Source properties", i.e. what properties? Thank you!

Thank you for that. I'm using C++. I know that my code is very basic but I quote it here so that you can get an idea of what it is doing. The program sets up the instance of the OPC object at the begining and then calls the functions get_point(...) and out(...) once every loop. I have removed the code for the function setup(...) as it just contains the definition of the ItemArrays and server names and such and thus there is propriatary info in there.Once the output is "unknown error", it keeps outputting just that at every single read attempt.******************************************************************Header File opc.h#ifndef OPC_H#define OPC_H#include "archive.h"#include "conversion.h"#define _ATL_CSTRING_EXPLICIT_CONSTRUCTORS // some CString constructors will be explicit#include #include #include #include #include #include #include #include #include #include #import "libid:FAB7A1E3-3B79-4292-9C3A-DF39A6F65EC1" version(5.1) // EasyOpcLibusing namespace EasyOpcLib;using namespace std;class OPC{ private: bool toggle; int number_in_items; int number_out_items; string machine; string server; CComSafeArray *ItemInArray; CComSafeArray *ItemOutArray; CComVariant vMissing; CComSafeArray * values; basic_info * info; time_t now; conversion conv; IEasyDAClientPtr *dac; public: OPC(); ~OPC(); void log_in() { dac = new IEasyDAClientPtr(__uuidof(EasyDAClient)); }; void setup(basic_info *in); bool get_point(archive_entry * entry); void out(archive_entry * entry, vector *opt, bool suggest);};#endif******************************************************************Code file opc.cpp#include "OPC.h"OPC::OPC(){ toggle = true; vMissing.vt = VT_ERROR; dac = NULL; CoInitialize(NULL); // Initialize the COM library}OPC::~OPC(){ CoUninitialize();}bool OPC::get_point(archive_entry * entry){ int i; double value = 0.0; if(dac == NULL) log_in(); CComVariant vResults((*dac)->ReadMultipleItems(machine.c_str(), server.c_str(), CComVariant(LPSAFEARRAY(*ItemInArray)), vMissing)); time(&now); // get the current time for the newly read point. entry->time = now; CComSafeArray ResultArray(vResults.parray); for(i = ResultArray.GetLowerBound(0); i <= ResultArray.GetUpperBound(0); ++i) { IDAVtqResultPtr DAVtqResultPtr(ResultArray); if(DAVtqResultPtr->Exception == NULL) // only if this is NULL, is the result valid. { IDAVtqPtr DAVtqPtr(DAVtqResultPtr->Vtq); // contains value, timestamp, quality. value = DAVtqPtr->Value.dblVal; // retrieves the value. It *must* be a double as the variant will contain an R8 value! entry->data = (float) value; // now save values to the passed entry. } else // we have an exception. { // Handle failure here: you can use properties such as COMExceptionPtr->HResult, COMExceptionPtr->Message. ICOMExceptionPtr COMExceptionPtr = DAVtqResultPtr->Exception; printf("%s at ", conv.convert_time(now).c_str()); _tprintf(_T("%d: failure: %s\n"), i, COLE2T(COMExceptionPtr->Message)); entry->data = info->special_value; } } ResultArray.Destroy(); // Release all interface pointers BEFORE calling CoUninitialize() vResults.Clear(); return true;}void OPC::out(archive_entry * entry, vector *opt, bool suggest){ if(suggest == true) { values->SetAt(0, CComVariant(opt->at(45))); values->SetAt(1, CComVariant(opt->at(42))); } else { values->SetAt(0, CComVariant(entry->data[info->column_map[8872]])); values->SetAt(1, CComVariant(entry->data[info->column_map[8704]])); } values->SetAt(2, CComVariant(entry->data[info->column_map[9002]])); values->SetAt(3, CComVariant(entry->data[info->column_map[1030]])); if(toggle == true) { values->SetAt(4, CComVariant(1.0)); toggle = false; } else { values->SetAt(4, CComVariant(0.0)); toggle = true; } CComSafeArray saResults; saResults.Attach((*dac)->WriteMultipleItemValues(machine.c_str(), server.c_str(), CComVariant(*ItemOutArray), CComVariant(*values)).parray);}

Hi there,
I have a very simple program that reads some items from an OPC server every few seconds based on the simple read item sample provided with QuickOPC COM. This goes well for some time. Sometimes I get exceptions and then I output the message like in the example. Whenever the message actually contains a real message all is well. At random intervals however (roughly once in two weeks) the exception message says "unknown error" and then the read process never recovers. The connection to the server seems to be broken. However both the server and the client application are still running and the network is fine. Thus the error must somehow be internal to QuickOPC. I have tried to re-connect but after I do this for a few times, the connection is irreparably severed and I need to reboot my client machine. After that it runs fine again. What can I do?
Thank you! Best, Patrick