Please try to use this line instead: In order to keep the example code short, it does not check for error conditions. So, AttributeData can be legitimately null in case of communication problems, but in such case the example code would crash. A production quality code should test the eventArgs.Exception first.

So, there is a possibility that the exception is caused by this.

Just installed QuickOPC Version 2016.2.
I get the same exception in Delphi XE4 in the module _EasyUAClient.SubscribeMonitoredItem, row:
WriteLn (eventArgs.Arguments.NodeDescriptor.ToString,':',eventargs.AttributeData.ToString)

So I can't see the result.
Single read works.
The re-import the Type Libraries didn't help.

Please advise...

This problem was caused by obsoleted imports in the examples (we distribute the Delphi code generated from our Type Libraries together with the examples, to make it easier to build them; however anyone can re-import the Type Libraries into Delphi at any time, and the steps for that are explained in the documentation).

We have fixed this in the recent build, QuickOPC 5.35.414.1.

Please download it from our Web site, re-install, and re-build your project(s).

Best regards

Hello i am using Delphi XE 7 and try to test your OP-Example óf UADocExamples.

If i try to Monitore items i always get an exception in

WriteLn(eventArgs.Arguments.NodeDescriptor.ToString, ': ',
eventArgs.AttributeData.ToString);
(see attached file)

I also get the exception if i use
WriteLn(eventArgs.Arguments.NodeDescriptor.ToString);
or
WriteLn(eventArgs.AttributeData.ToString);
instead

Only if i use WriteLn(eventArgs.Arguments.ToString);
I can see the results.

Can you tell me how i can get only the value of the changed item and if possible not as string but as variant?

Kind regads
Dirk

Hello,

i am using Delphi XE 7 and try to run your example UADocExamples

In Module _EasyUAClient.SubscribeMonitoredItem.Main.inc i always get an error

Exception in Class $C0000005 : Access Violation at 0x005e8132: read of adress 0x8f621b56


This happens always in line 25

WriteLn (eventArgs.Arguments.NodeDescriptor.ToString,':',eventargs.AttributeData.ToString)


I also get an exception if i use
WriteLn (eventArgs.Arguments.NodeDescriptor.ToString)
or
WriteLn (eventargs.AttributeData.ToString)
instead.

But i get no exception if use writeln(eventargs.Arguments.ToString) instead.


What can i do to run this example ?


Second question :

I want to get the value of the changed node as Variant an not as string is there a property that delivers variant?

Kind regards Dirk.