AdsClientExtensions.WhenNotification Method (IAdsConnection, ISymbolCollection)
Gets an observable sequence of Notification objects.
Namespace: TwinCAT.Ads.Reactive
Assembly: TwinCAT.Ads.Reactive (in
TwinCAT.Ads.Reactive.dll) Version: 6.0.328+39e3229
Syntax
C#
public static IObservable<SymbolValueNotification> WhenNotification(
this IAdsConnection connection,
ISymbolCollection symbols
)
Parameters
connection |
Type: TwinCAT.Ads.IAdsConnection |
symbols |
Type: TwinCAT.TypeSystem.ISymbolCollection |
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IAdsConnection. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
Examples
The following sample shows how observe Value changed Notifications with the reactive AdsClientExtensions
Observe changing ADS Symbols with reactive extensions.
// To Test the Observer run a project on the local PLC System (Port 851)
using (AdsClient client = new AdsClient())
{
// Connect to target
client.Connect(new AmsAddress(AmsNetId.Local, 851));
// Create Symbol information
var symbolLoader = SymbolLoaderFactory.Create(client, SymbolLoaderSettings.Default);
int eventCount = 1;
// Reactive Notification Handler
var valueObserver = Observer.Create<SymbolValueNotification>(not =>
{
Console.WriteLine(string.Format("{0} {1:u} {2} = '{3}' ({4})", eventCount++, not.TimeStamp, not.Symbol.InstancePath, not.Value, not.Symbol.DataType));
}
);
// Collect the symbols that are registered as Notification sources for their changed values.
SymbolCollection notificationSymbols = new SymbolCollection();
IArrayInstance taskInfo = (IArrayInstance)symbolLoader.Symbols["TwinCAT_SystemInfoVarList._TaskInfo"];
foreach(ISymbol element in taskInfo.Elements)
{
ISymbol cycleCount = element.SubSymbols["CycleCount"];
ISymbol lastExecTime = element.SubSymbols["LastExecTime"];
notificationSymbols.Add(cycleCount);
notificationSymbols.Add(lastExecTime);
}
// Create a subscription for the first 200 Notifications on Symbol Value changes.
IDisposable subscription = client.WhenNotification(notificationSymbols,NotificationSettings.Default).Take(200).Subscribe(valueObserver);
Console.ReadKey(); // Wait for Key press
subscription.Dispose(); // Dispose the Subscription
}