Thanks for looking into this issue.

I also see the null reference exception if the Refresh Current Network button gets clicked too fast. It looks like I didn't disable the Refresh Current Network button while the background worker is running in this test version.

The Refresh Current Network button shouldn't be pressed until after you've opened up the Network Tree node to view your machine.

With regards to your possible parallel calls issue, do the calls made by the Subscribed Items run in parallel with the BrowseServers? Something like that could explain why that SEHException occurs randomly and why it only occurs when there are OPC Item Subscriptions active. Could OPC communications duration be longer with some of my OPC Test Servers which could increase the likelihood of these calls to overlap?

I've created a small application using SharpDevelop that reproduces the SEHException. Could you please provide an e-mail address so that I can send it to you.

Also, I've noticed since switching to 5.23, my main application throws the following exception almost every time I close the program:

System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at COCKTopicParameters.=(COCKTopicParameters* , COCKTopicParameters* rhs)
at COCKTopicParameters.{ctor}(COCKTopicParameters* , COCKTopicParameters* Parameters, Int32 )
at OpcLabs.EasyOpcRaw.DataAccess.RawEasyDATopicParameters.Done(Boolean finalize)
at OpcLabs.EasyOpcRaw.DataAccess.RawEasyDATopicParameters.!RawEasyDATopicParameters()
at OpcLabs.EasyOpcRaw.DataAccess.RawEasyDATopicParameters.Dispose(Boolean )
at OpcLabs.EasyOpcRaw.DataAccess.RawEasyDATopicParameters.Finalize()

This exception seems to be caused by setting the following at the beginning of the program:
EasyDAClient.SharedParameters.Client.ClientReconnectDelay = 10000;
EasyDAClient.SharedParameters.Client.ServerFailedReconnectDelay = 10000;
EasyDAClient.SharedParameters.Client.ServerShutdownReconnectDelay = 10000;

Talk to you soon,

Tom.

Thanks for the quick response!

I just built the program using 5.23. I am still having the same issues where the browseServers() function occasionally throws a SEHException and the EasyDAClient never recovers and sometimes crashes.

Some new info:

-If running in release mode, the issue seems to occur less frequently.

-Calling browseServers() immediately following a response increases the likelihood of throwing the SEHException.

-The following error occurred right after I tried to close the program after causing the initial SEHException issue.

System.Runtime.InteropServices.SEHException: External component has thrown an exception.
at AfxThrowInvalidArgException()
at CConsumer.{dtor}(CConsumer* )
at COCKConsumerBase.{dtor}(COCKConsumerBase* )
at COCKConsumer.{dtor}(COCKConsumer* )
at CEDAConsumer.{dtor}(CEDAConsumer* )
at CEDAAbstractEngine.{dtor}(CEDAAbstractEngine* )
at OpcLabs.EasyOpcRaw.DataAccess.CDAInnerEngine.{dtor}(CDAInnerEngine* )
at OpcLabs.EasyOpcRaw.DataAccess.CDAInnerEngine.__vbaseDtor(CDAInnerEngine* )
at OpcLabs.EasyOpcRaw.DataAccess.CDAInnerEngine.__vecDelDtor(CDAInnerEngine* , UInt32 )
at CEasyAbstractModule.DestroyDAEngine(CEasyAbstractModule* , CEDAAbstractEngine** pDAEngine)
at CEasyAbstractModule.ModuleStop(CEasyAbstractModule* )
at OpcLabs.EasyOpcRaw.CInnerModule.ModuleStop(CInnerModule* )
at OpcLabs.EasyOpcRaw.CInnerModule.{dtor}(CInnerModule* )
at ?A0x5e6d74c4.??__F_Module@@YMXXZ()
at _exit_callback()
at <CrtImplementationDetails>.LanguageSupport._UninitializeDefaultDomain(Void* cookie)
at <CrtImplementationDetails>.LanguageSupport.UninitializeDefaultDomain()
at <CrtImplementationDetails>.LanguageSupport.DomainUnload(Object source, EventArgs arguments)
at <CrtImplementationDetails>.ModuleUninitializer.SingletonDomainUnload(Object source, EventArgs arguments)


I can look to spend time creating a test program to demonstrate my issue if required.

Tom.

When I call BrowseServers() while my program is subscribed to multiple items I frequently (sometimes, but not always) throw this exception:

System.Runtime.InteropServices.SEHException (0x80004005): External component has thrown an exception.
at OpcLabs.EasyOpcRaw.DataAccess.CDAInnerEngine.ExecuteAlgorithm(CDAInnerEngine* , CSynchronizedAlgorithm* Algorithm)
at CEDAAbstractEngine.BrowseServers(CEDAAbstractEngine* , Char* MachineIsolator, Char* MachineName, CEDAAbstractMode* pMode, CEasyServerElementMap* ServerElementMap)
at OpcLabs.EasyOpcRaw.DataAccess.RawEasyDAClient.BrowseServers(String machineName)
at OpcLabs.EasyOpc.DataAccess.EasyDAClient.BrowseServers(String machineName)


The program is trying to scan itself for OPC Servers. Some of these servers' OPC Items are subscribed to by an EasyDAClient instantiated by the MainForm thread. While subscribed, a background worker thread's EasyDAClient instance tries to call BrowseServers().

The BrowseServers() call throws the Exception above. Once this exception occurs, any future call to BrowseServers() fails with the same exception throughout the lifetime of the program. Too many attempts in a row after the exception is thrown freezes or crashes the program completely.

Restarting the program seems to help.

The program is a C Sharp program. I am using EasyDAClient Dot Net version 5.21 with SharpDevelop in Debug Mode on the Windows 7 x64 bit OS. The program's platform is x86 and Dot Net 4.0 Client.

Any help would be greatly appreciated.

Tom.