This cannot be answered without having the information about the device (first), and information about how the OPC Server present it through OPC, (second). QuickOPC only consumes what is in the OPC server
Good method for transferring such data may be OPC-HDA (Historical Data Access); however QuickOPC currently does not support it, and PiiGAB OPC server neither.
Sometimes, an alternative method is used to transfer such data. For example, some electricity meters store load profile data as series of event records, and this can be transferred as an array. Such array can be communicated through OPC-DA (Data Access) and then processed by the application.
All of the above is however purely for illustration - with a concrete device and server to connect to, one needs to figure what they support and how they do it.

You are most likely right, however it may depend on the specific device.

Yes, BrowseLeaves can be used; BrowseNodes is a generalized function that combines the functionality of BrowseLeaves and BrowseBranches.
I have created the example you might have been looking for: It is in "Knowledge Base", under QON-KB-4. How to browse OPC address space in C#, and read the items found. If you download the Bonus Pack from this site again now, you will find that this example is included too.
Let me know if you need anything more.
Best regards

We (OPC Labs) sell (among others) a product caled QuickOPC, which is a tool/component for developers to easily integrate OPC client functionality into applications. The component is server-agnostic: It can connect to any OPC Data Access server. We do not sell or produce any MBus equipment, MBus/IP convertors, or MBus OPC Server. It looks like that you are using PiiGAB MBus OPC server and IP convertors; questions about those products should be directed to PiiGAB.
There is partnership between OPC Labs and PiiGAB in the sense that we have been instrumental to PiiGAB in developing their MBus OPC Server, and PiiGAB uses and bundles the QuickOPC functionality with their products.
Re

as I can see (and pointed out), it refering to the dll files when open the browse-items folder. Please correct me if I'm wrong!

private OpcLabs.EasyOpc.DataAccess.Forms.OpcDAItemDialog opcDAItemDialog1;

If what you mean is that the code that provides the user interface (form) for browsing the items is in a compiled assembly with no source code provided, then you are right - this assembly is part of the QuickOPC product itself, which is not provided with its source code. The code inside the form, however, uses no secret - it is based on the BrowseNodes method that is documented (see e.g. www.opclabs.com/onlinedocs/Qui... or www.opclabs.com/onlinedocs/Qui...) and you have successfully tried before. I will prepare some example in C# which illustrates with some more detail how the browsing can be done from your code. Please allow a little time before I have it ready for you.
Best regards

[below is a restored post from <span style="font-size: 10pt; color: #403f3f; font-family: "Tahoma","sans-serif"; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">3/2/2011 10:45:05 AM, out of sequence]
Ok.. now I seem to go a little step further!
Dictionary<string, DANodeElement> nodes;
DANodeFilter daf = new DANodeFilter()
{
BrowseFilter = DABrowseFilter.All,
AccessRightsFilter = DAAccessRights.Both,
DataTypeFilter = VarType.Empty,
ElementNameFilter = "",
VendorFilter = ""
};

EasyDAClient clt = new EasyDAClient();
ServerDescriptor sd = new ServerDescriptor("","PiiGAB.MBus.2");

Dictionary<string, DANodeElement> srv = clt.BrowseBranches(sd);

foreach (DANodeElement elm in srv.Values)
{
//Branches
Console.WriteLine("{0} = {1}", elm.Name, elm.ItemId);

if (elm.HasChildren)
{
//Nodes
nodes = clt.BrowseNodes(sd, elm.ItemId, daf); Console.WriteLine("\nLeafs ({0})", nodes.Count());
foreach (DANodeElement elm2 in nodes.Values)
Console.WriteLine("{0} = {1}, elm2.Name, elm2.ItemId);
}
}
<span style="font-size: 12pt; font-family: "Times New Roman","serif"; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">However this was just about time . There are still some interesting questions in my last post, that does not relate to this success.

Oh, i edited the post, because I got further on and the questions was obsolete (why keep them).

The purpose of this forum is to help others as well. The fact that the post contains something that has been resolved is the very reason for keeping it, not for removing it. I will put back the part that I can restore.
Now to your new post:
The demo application code is actually pretty straightforward. If by "hided inside compilations" you mean that you do not have the source code, then I just need to point it to the right place. In the core product, the Demo application is just in binary. When you install the Bonus pack, you get the source code of the Demo application: It is under Examples\CSharp\VS2010\WindowsForms\EasyOpcDANetDemo1 subfolder (or VS2008 instead of VS2010, or VBNET instead of CSharp). Let me know if the part that is giving you poblems is finding how to identify the information in the server (browsing for ItemIDs), or obtaining the information from the server (reading), and I can then help you further.
Yes, you might say that the OPC server creates "aliases" to data items in the device(s). The precise way this is done is server-specific; there might be a CSV file for the PiiGAB MBus OPC Server that defines the server's "address space" in part or as a whole. For specifics about this, I suggest that you contact PiiGAB (I can facilitate that for you if you ask me to).
Best regards,
Zbynek Zahradnik