在 a.Net Core OPC UA 客户端上使用基于事件的 MonitoredItem 处理 Sinumerik 警报

Question

I'm trying to monitor alarm events on a OPC UA client utilizing event based monitored items. I subscribe to the node: ns=2;s=Sinumerik and add the corresponding attributes and filters. Later on I handle the notification on a OnNotification() method as shown in the code below.

var list = new List<MonitoredItem> { new MonitoredItem(_subscription.DefaultItem) {StartNodeId = "ns=2;s=Sinumerik" } };

foreach (MonitoredItem item in list)
{
    item.AttributeId = Attributes.EventNotifier;
    item.MonitoringMode = MonitoringMode.Reporting;
    item.SamplingInterval = -1;
    item.QueueSize = 100;
    item.DiscardOldest = false;
    EventFilter filter = new EventFilter();
    filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.Message);
    filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.Severity);
    item.Filter = filter;
    item.Notification += OnNotification;
}

_subscriptions[subscriptionNum].Create();
_subscriptions[subscriptionNum].ApplyChanges();

The OnNotification() method looks like this:

private void OnNotification(MonitoredItem item, MonitoredItemNotificationEventArgs e)
{
    foreach (var value in item.DequeueValues())
    {
        Console.WriteLine("Display Name: " + item.DisplayName + "Value: " + value.Value);
    }
}

I receive the event notification but there are no Values in the MonitoredItem.

Is this the correct way to monitor event based monitored items for Sinumerik Alarms using OPC UA?

Answer 1

You are subscribing for Events, not other data attributes, so try item.DequeueEvents() instead.