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No notification for disconnect

support
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08 Feb 2016 10:26 #3826 by support

Replied by support on topic No notification for disconnect

Great.

For readers of the forum - always check .Exception in the incoming event arguments or result objects first.

Best regards

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08 Feb 2016 10:17 #3825 by giles

Replied by giles on topic No notification for disconnect

Ah sorry you are right - AttibuteData was null so I was getting a silent exception in my code

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08 Feb 2016 09:57 #3824 by support

Replied by support on topic No notification for disconnect

In general, the answer is No. You *should* get a notification in such case.

Can you please answer following questions:

1. Which version and build of QuickOPC are you using?
2. Is the server local or remote?
3. Which protocol (opc.tcp:, http: ?)
4. What precisely do you mean by "...the server gets switched off". Is it referring to a loss of power of a remote machine? Or a force termination of the server process? Or a properly shutdown of it? Or a properly shutdown of the whole machine? Etc.
5. How long have you waited after that?
6. Do you test the .Exception of the incoming EasyUAMonitoredItemChangedEventArgs ? Can you post that piece of code here?

Thank you, and best regards

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08 Feb 2016 09:37 #3823 by giles

No notification for disconnect was created by giles

I am connecting to a kepware server using UAMonitoredItemChangedObservable. I find I don't get notified if the server gets switched off. Is this expected.

For reference I have ended up pinging the server every 60 seconds as below I wonder if there is a better solution you could suggest ? (I realise could use one common tag for the server and channel rather than pinging each tag)

Code:

public class ItemValue
    {
        public object Value { get ; set;}
        public bool Good { get;set;}

        static public IObservable<ItemValue> UaObservable(object status, string endpoint, string node, int updateInterval, string type)
        {
            var args = new EasyUAMonitoredItemArguments(
                status,
                endpoint,
                node,
                updateInterval
            );
            var uaClient = new EasyUAClient();


            var check =  (Observable.Return<long>(0).Concat(Observable.Interval(
                TimeSpan.FromSeconds(60))).Select(t =>
                    {
                        try
                        {
                            return uaClient.Read(
                                endpoint,
                                node
                            ).HasGoodStatus;
                        }
                        catch (Exception)
                        {
                            return false;
                        } 
                    }
                ).Distinct());


            return check.SelectMany(c =>
            {
                if (!c)
                {
                    return Observable.Return(new ItemValue{Good=false});
                }
                else
                {
                    IObservable<EasyUAMonitoredItemChangedEventArgs> ret = null;
                    switch (type)
                    {
                        case "int":
                            ret = UAMonitoredItemChangedObservable.Create<int>(args);
                            break;
                        case "bool":
                            ret = UAMonitoredItemChangedObservable.Create<bool>(args);
                            break;
                        case "double":
                            ret = UAMonitoredItemChangedObservable.Create<double>(args);
                            break;
                        case "float":
                            ret = UAMonitoredItemChangedObservable.Create<Single>(args);
                            break;
                        default:
                            ret = UAMonitoredItemChangedObservable.Create<string>(args);
                            break;
                    }
                    return ret.Select(
                        r => new ItemValue
                        {
                            Value = r.AttributeData != null ? r.AttributeData.Value : null,
                            Good = r.AttributeData != null && r.AttributeData.StatusCode.ToString().StartsWith("Good")
                        }
                    );
                }
            });
            

            
        } 
    }

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