Dear Sir,
we have some very basic examples in Delphi for UA Alarms&Conditions that come with the product (just look under the install directory, ExamplesCom\OP). The reason why we do not have more examples is because there is such a big number of tools and languages from which QuickOPC can be used, that it makes it impossible to provide high number of examples in all of them. The Delphi examples show OPC UA Alarms&Conditions, but currently without filtering. It look e.g. like this:
Code:
type
TClientEventHandlers2 = class
procedure OnEventNotification(
ASender: TObject;
sender: OleVariant;
const eventArgs: _EasyUAEventNotificationEventArgs);
end;
procedure TClientEventHandlers2.OnEventNotification(
ASender: TObject;
sender: OleVariant;
const eventArgs: _EasyUAEventNotificationEventArgs);
begin
// Display the event
WriteLn(eventArgs.ToString);
end;
class procedure SubscribeEvent.Main;
var
Client: TEasyUAClient;
ClientEventHandlers2: TClientEventHandlers2;
begin
// Instantiate the client object and hook events
Client := TEasyUAClient.Create(nil);
ClientEventHandlers2 := TClientEventHandlers2.Create;
Client.OnEventNotification := ClientEventHandlers2.OnEventNotification;
WriteLn('Subscribing...');
Client.SubscribeEvent(
'opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer',
'nsu=http://opcfoundation.org/UA/;i=2253', // UAObjectIds.Server
1000);
WriteLn('Processing event notifications for 30 seconds...');
PumpSleep(30*1000);
//WriteLn('Unsubscribing...');
Client.UnsubscribeAllMonitoredItems;
WriteLn('Waiting for 5 seconds...');
PumpSleep(5*1000);
end;
It can also be done with hooking events (using a "pull" mechanism), and there is an example for it as well in the product.
As to the filter: You wrote "it failed". That's not enough information. What precisely have you tried, and what were the results? I would be more than happy to help, and even we can even commonly create some FreePascal examples that would then help other users.
Creating a filter can be fairly complicated - because UA is very flexible in this manner. Below some example in C#. Once you understand what is going on, we can try to do an equivalent, or something similar, in Delphi or FreePascal.
Code:
class SelectClauses
{
public static void Main()
{
// Instantiate the client object and hook events
var easyUAClient = new EasyUAClient();
easyUAClient.EventNotification += easyUAClient_EventNotification;
Console.WriteLine("Subscribing...");
easyUAClient.SubscribeEvent(
"opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer",
UAObjectIds.Server,
1000,
new UAAttributeFieldCollection
{
// Select specific fields using standard operand symbols
UABaseEventObject.Operands.NodeId,
UABaseEventObject.Operands.SourceNode,
UABaseEventObject.Operands.SourceName,
UABaseEventObject.Operands.Time,
// Select specific fields using an event type ID and a simple relative path
UAFilterElements.SimpleAttribute(UAObjectTypeIds.BaseEventType, "/Message"),
UAFilterElements.SimpleAttribute(UAObjectTypeIds.BaseEventType, "/Severity"),
});
Console.WriteLine("Processing event notifications for 30 seconds...");
System.Threading.Thread.Sleep(30 * 1000);
Console.WriteLine("Unsubscribing...");
easyUAClient.UnsubscribeAllMonitoredItems();
Console.WriteLine("Waiting for 5 seconds...");
System.Threading.Thread.Sleep(5 * 1000);
}
static void easyUAClient_EventNotification(object sender, EasyUAEventNotificationEventArgs e)
{
Console.WriteLine();
// Display the event
if (e.EventData == null)
{
Console.WriteLine(e);
return;
}
Console.WriteLine("All fields:");
foreach (KeyValuePair<UAAttributeField, ValueResult> pair in e.EventData.FieldResults)
{
UAAttributeField attributeField = pair.Key;
ValueResult valueResult = pair.Value;
Console.WriteLine(" {0} -> {1}", attributeField, valueResult);
}
// Extracting a specific field using a standard operand symbol
Console.WriteLine("Source name: {0}",
e.EventData.FieldResults[UABaseEventObject.Operands.SourceName]);
// Extracting a specific field using an event type ID and a simple relative path
Console.WriteLine("Message: {0}",
e.EventData.FieldResults[UAFilterElements.SimpleAttribute(UAObjectTypeIds.BaseEventType, "/Message")]);
}
}
and
Code:
class WhereClause
{
public static void Main()
{
// Instantiate the client object and hook events
var easyUAClient = new EasyUAClient();
easyUAClient.EventNotification += easyUAClient_EventNotification;
Console.WriteLine("Subscribing...");
easyUAClient.SubscribeEvent(
"opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer",
UAObjectIds.Server,
1000,
new UAEventFilterBuilder(
// Either the severity is >= 500, or the event comes from a specified source node
UAFilterElements.Or(
UAFilterElements.GreaterThanOrEqual(UABaseEventObject.Operands.Severity, 500),
UAFilterElements.Equals(
UABaseEventObject.Operands.SourceNode,
new UANodeId("nsu=http://opcfoundation.org/Quickstarts/AlarmCondition;ns=2;s=1:Metals/SouthMotor"))),
UABaseEventObject.AllFields));
Console.WriteLine("Processing event notifications for 30 seconds...");
System.Threading.Thread.Sleep(30 * 1000);
Console.WriteLine("Unsubscribing...");
easyUAClient.UnsubscribeAllMonitoredItems();
Console.WriteLine("Waiting for 5 seconds...");
System.Threading.Thread.Sleep(5 * 1000);
}
static void easyUAClient_EventNotification(object sender, EasyUAEventNotificationEventArgs e)
{
// Display the event
Console.WriteLine(e);
}
}
Best regards
