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QuickOPC install in Visual Studio 2010 C++. ReadMultipleItems example

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28 May 2014 06:31 #2006 by support
I do not see a product related question here, sorry.

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27 May 2014 07:18 - 27 May 2014 07:22 #2003 by forestro
Hello,

I created an OPC class to acess OPC server which is used in another class. I don't use the main function and I would like to use a signal when there is an itemchanged event.

In attachments : OPC_Client.h (header file) and OPC_Client.cpp
Attachments:
Last edit: 27 May 2014 07:22 by forestro.

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27 May 2014 06:28 #2001 by support
The example in C++ I referred to (www.opclabs.com/forum/com-reading-writing-subscriptions-prop...scribemultipleitems-in-vc#1996 ) does almost exactly the same thing as the C# example you listed, i.e. it subscribes to multiple OPC items, and prints out the values as they come in.

The other C++ example in this thread reads the values explicitly, and also prints them out.
If needed, the two examples can be combined together.

What precisely is it that you don't understand?

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26 May 2014 13:32 #1999 by forestro
Hello,

Thanks you for this example but I need an example in c++ as C# example :

// This example shows how subscribe to changes of multiple items and display the value of the item with each change.
2
3using JetBrains.Annotations;
4using OpcLabs.EasyOpc.DataAccess;
5using System;
6using System.Threading;
7
8namespace DocExamples
9{
10 namespace _EasyDAClient
11 {
12 partial class SubscribeMultipleItems
13 {
14 public static void Main()
15 {
16 using (var easyDAClient = new EasyDAClient())
17 {
18 easyDAClient.ItemChanged += easyDAClient_ItemChanged;
19
20 easyDAClient.SubscribeMultipleItems(
21 new[] {
22 new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, null),
23 new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (1 min)", 1000, null),
24 new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Sine (1 min)", 1000, null),
25 new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 1000, null)
26 });
27
28 Console.WriteLine("Processing item changed events for 1 minute...");
29 Thread.Sleep(60 * 1000);
30 }
31 }
32
33 // Item changed event handler
34 static void easyDAClient_ItemChanged([NotNull] object sender, [NotNull] EasyDAItemChangedEventArgs e)
35 {
36 Console.WriteLine("{0}: {1}", e.ItemDescriptor.ItemId, e.Vtq);
37 }
38 }
39 }
40}

I created an OPC client class which use subscribe and read item. I would like to read item when it changes. I don't understand your example and how to add it in my class.

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26 May 2014 08:47 #1997 by support

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26 May 2014 08:36 #1995 by support
Hello.

Regarding instantiating the EasyDAClient in a file different from the declaration: Not sure what you mean - can you describe the problem in more detail?

Regarding "ReadItems" example: under the QuickOpcComCppExamples solution, there is Win32\ReadMultipleItems example. Its main part looks like this:

 
// Copyright (c) CODE Consulting and Development, s.r.o., Plzen. All rights reserved.
// ReadMultipleItems.cpp : Defines the entry point for the console application.
//
 
#include "stdafx.h"
#include <atlsafe.h>
#include <comutil.h>
 
#import "libid:FAB7A1E3-3B79-4292-9C3A-DF39A6F65EC1" version(5.2)	// EasyOpcLib
using namespace EasyOpcLib;
 
int _tmain(int argc, _TCHAR* argv[])
{
	// Initialize the COM library
	CoInitialize(NULL);
 
	// Instatiate the EasyOPC-DA client object
	IEasyDAClientPtr EasyDAClientPtr(__uuidof(EasyDAClient));
 
	CComSafeArray<BSTR> ItemIdArray(4);
	ItemIdArray[0] = _T("Simulation.Random");
	ItemIdArray[1] = _T("Trends.Ramp (1 min)");
	ItemIdArray[2] = _T("Trends.Sine (1 min)");
	ItemIdArray[3] = _T("Simulation.Register_I4");
 
	CComVariant vMissing;
	vMissing.vt = VT_ERROR;
 
	CComVariant vResults(EasyDAClientPtr->ReadMultipleItems(_T(""), _T("OPCLabs.KitServer.2"), 
		CComVariant(ItemIdArray.Detach()), vMissing));
 
	CComSafeArray<VARIANT> ResultArray(vResults.parray);
	for (int i = ResultArray.GetLowerBound(0); i <= ResultArray.GetUpperBound(0); i++)
	{
		IDAVtqResultPtr DAVtqResultPtr(ResultArray[i]);
		IDAVtqPtr DAVtqPtr(DAVtqResultPtr->Vtq);
		_tprintf(_T("results(%d).Vtq.ToString(): %s\n"), i, DAVtqPtr->ToString().bstrVal);
	}
 
	// Release all interface pointers BEFORE calling CoUninitialize()
	ResultArray.Destroy();
	vResults.Clear();
	EasyDAClientPtr = NULL;
 
	CoUninitialize();
 
	TCHAR line[80];
	_putts(_T("Press Enter to continue..."));
	_fgetts(line, sizeof(line), stdin);
	return 0;
}
 

An example with ItemChanged event: will be in a separate post.

Best regards

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22 May 2014 08:57 #1988 by forestro
Hello,

I need an example of using of itemChanged event for one item in Visual Studio c++ COM project.

Thanks you.

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21 May 2014 08:57 #1986 by forestro
Hello,

I referred to erros generated by IntelliSense. This problem is resolved.
I have a lot of problems to program with QuickOPC-COM. Do you have an example to Instatiate the EasyOPC-DA client object in a file different of the declaration. And examples with ReadItems, subsribeitem using std::string and an example with itemchanged event.

Thanks you.

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19 May 2014 21:03 #1982 by support
Are you referring to errors generated by IntelliSense, or actual build errors?

If you are describing IntelliSense, the solution is: ignore them.
If you are dealing with build errors, can you do a Rebuild of our original project, and post a full content of the Output windows here?

Thank you.

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19 May 2014 08:57 #1978 by forestro
Hello,

I have used the second possibility with the "COM Visual C++ Example (VS 2008).
I copied these sentences and paste in my header file :

#import "libid:FAB7A1E3-3B79-4292-9C3A-DF39A6F65EC1" version(5.2) exclude("_IEasyDAClientEvents") // EasyOpcDALib
#import "libid:965A3842-AEEA-4DF9-9241-28B963F76E24" version(5.2) // OPCUserObjects

using namespace EasyOpcLib;
using namespace OPCUserObjects;

There are the same error in my project and in your project : "impossible to open the source file".

Are there files to add in my project ?

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