You still do not understand. I will try again.

There is no way to make OPC UA Read without specifying some MaxAge value (special for value cache or device, or some concrete number of milliseconds). This refers to what happens "on the wire".

QuickOPC has various various methods that, in the end, call the OPC UA Read service. Some of them allow you to specify the maximum age, some of them don't (and they use some default) - but even if there is no maximum age in the QuickOPC method, this does not mean that there is none being used on the wire. When there is no maximum age in the QuickOPC method call, a default is used; the default is Int32.MaxValue, which denotes a "cache" read.

In QuickOPC, for a particular OPC UA service, there is always on "universal" method that allows you to pass in everything possible, and also get back the maximum from what the OPC UA service call actually provides. For the OPC UA "Read" service, this "all-capable" QuickOPC method is ReadMultiple.

In addition to the "all-capable" method, there may be some additional methods that build on top of it, and make it easier to call it in some common cases. In .NET, there are literally tens of overloads for the methods, allowing various combinations of arguments. In COM (which has to be used to interface from .NET to Delphi), multiple overloads with the same name are not possible, and the number of these "extra" methods is smaller.

The "Read" method is one of the additional methods. It just puts together arguments for ReadMultiple, then calls ReadMultiple with one argument in the array, then extracts the single result it returns. No magic.

So, if you want to read one node in Delphi, and want to pass in a maximum age, you will simply use ReadMultiple instead, give it the array of arguments with one element (and the proper maximum age), and you are done.

Regards.

Hello. I do not understand your post.

Ad 1. MaxAge value is _always_ specified by any OPC UA client to OPC UA server when a Read service is called. There is no way around it. The MaxAge can be 0 (for reads from the data source), it can be set to reads from cache, or to a any desired value in milliseconds. QuickOPC cannot be different - it always passes a MaxAge. And you can specify the maximum age in the parameters for the Read. It is up to you which value you choose. If any of the values has advantages or disadvantages for you, or does not behave as you think it should, QuickOPC has nothing to do with it - it just uses the value you specify.

To your question : "How can we improve the performance using MaxAge = 0".
This is a question for Softing.

To your question: Why doesn't the "ReadMultiple" function read directly from Server without using MaxAge?
As I explained, there is no way to read "without MaxAge" (see OPC UA Spec Part, chapter :Read Service Parameters). You can, however, use any value you like for MaxAge (including special values "device" or "cache"), and QuickOPC allows you to do so.

Ad 2. I am not sure you mean by "simple Read". Please explain. If, what you meant, was reading one node instead of multiple ones: The Read and ReadValue are simplifications to make coding easier when reading just one item. For them to remain simple, some parameters are not available. If you want to read one node and specify MaxAge, use ReadMultiple with one node.

Regards

I cannot verify the syntax at this moment, but when preparing arguments for ReadMultiple or ReadMultipleValues methods, you would add something like
Best regards

Hello,

one more thing: Didn't that say something about reading from Cache?
If their bug is in the fact that the cache is never updated unless there is a subscription, then you could change the Read parameters in QuickOPC e.g. to read from the Device.

Kind regards

Hello,

thank you for letting me know.

Kind regards