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How to subscribe to multiple OPC DA items, when amount of variables is changing?

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20 Dec 2023 12:02 #12493 by mut9bu
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20 Dec 2023 11:28 #12492 by support
Hello.
It seems to me that you can simply do
client.SubscribeMultipleItems(dAItemGroupArguments .ToArray());
Is that what you were looking for?
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20 Dec 2023 10:54 - 20 Dec 2023 11:13 #12491 by mut9bu
Hello

My console app has following arguments:
        public string ip_address = Environment.GetCommandLineArgs()[1];
        public string item_no = Environment.GetCommandLineArgs()[2];        
        public string item_1 = Environment.GetCommandLineArgs()[3];
        public string item_2 = Environment.GetCommandLineArgs()[4];
        public string item_3 = Environment.GetCommandLineArgs()[5];
        public string item_4 = Environment.GetCommandLineArgs()[6];
        public string item_5 = Environment.GetCommandLineArgs()7];
        public string item_6 = Environment.GetCommandLineArgs()[8];
        public string item_7 = Environment.GetCommandLineArgs()[9];
        public string item_8 = Environment.GetCommandLineArgs()[10];
        public string item_9 = Environment.GetCommandLineArgs()[11];
        public string item_10 = Environment.GetCommandLineArgs()[12];

Due to the item_no parameter I tried to define a list of items:
         List<DAItemGroupArguments> dAItemGroupArguments = new List<DAItemGroupArguments>();
 
         public void item_list()
         {
           for(int i = 0; i < Convert.ToInt16(item_no); i++)
            {
                dAItemGroupArguments.Add(new DAItemGroupArguments(ip, server, Environment.GetCommandLineArgs()[i+3], 1000, null));
            }
         }

So I should use always this list (or something similar) in the client.SubscribeMultipleItems(...) expression.
Last edit: 20 Dec 2023 11:13 by support.

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20 Dec 2023 10:42 #12490 by support
Hello.

It's easy to do. You just need to convert what you have into the form expected by the method. But I cannot answer it without knowing in which form (object types, their properties etc.) you get your items. Please share a piece of code illustrating that.

Regards

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20 Dec 2023 10:27 - 20 Dec 2023 10:40 #12489 by mut9bu
Hello

In my C# .net framework 4.7.2 app I am subscribing to multiple OPC DA items. But my app is called from a parent app with arguments. That means, the number of items and the item definitions come from the argument parameters and changing each time.

Normally I subscribe to 3 items with following code. How should I modify my code, so that I can sometimes for example subscribe to 2 items sometimes to 8 items , depending on the argument parameters? With other words I would like to use a List of items for the client.SubscribeMultipleItems expression. But couldn't find the correct way for this.
using (var client = new EasyDAClient())
            {
                client.ItemChanged += client_Main1_ItemChanged;
                client.SubscribeMultipleItems(
                    new[] {
                            new DAItemGroupArguments(ip, "OPC.IwSCP.1",item_def1, 1000, null),
                            new DAItemGroupArguments(ip, "OPC.IwSCP.1",item_def2, 1000, null),
                            new DAItemGroupArguments(ip, "OPC.IwSCP.1",item_def3, 1000, null),
                        }                    
                    );
            }
 
public void client_Main1_ItemChanged(object sender, EasyDAItemChangedEventArgs e)
        {
            if (e.Succeeded)
            {
                item_value = e.Vtq.ToString();
            }
            //
            else
            {
                Console.WriteLine($"{e.ErrorMessageBrief}");
            }
         }
Last edit: 20 Dec 2023 10:40 by support.

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