AdsConnection.AdsNotification Event

C#

public event EventHandler<AdsNotificationEventArgs> AdsNotification

Value

Type: System.EventHandler.AdsNotificationEventArgs.

Implements

IAdsNotifications.AdsNotification

Exceptions

Remarks

The Event Argument contains the raw data value of the notification, not marshalled to .NET types.

Examples

Example of receiving AdsNotification events.

Trigger on changed values by ADS Notifications

private async Task RegisterNotificationsAsync()
{
    CancellationToken cancel = CancellationToken.None;

    using (AdsClient client = new AdsClient())
    {
    // Add the Notification event handler
    client.AdsNotification += Client_AdsNotification2;

    // Connect to target
    client.Connect(AmsNetId.Local, 851);
    uint notificationHandle = 0;

    // Notification to a DINT Type (UINT32)
    // Check for change every 200 ms

    //byte[] notificationBuffer = new byte[sizeof(UInt32)];
    int size = sizeof(UInt32);

    ResultHandle result = await client.AddDeviceNotificationAsync("MAIN.nCounter", size, new NotificationSettings(AdsTransMode.OnChange, 200, 0), null, cancel);

    if (result.Succeeded)
    {
        notificationHandle = result.Handle;
        await Task.Delay(5000); // Wait asynchronously without blocking the UI Thread.
                    // Unregister the Event / Handle
        ResultAds result2 = await client.DeleteDeviceNotificationAsync(notificationHandle, cancel);
    }
    client.AdsNotification -= Client_AdsNotification2;
    }    
}

private void Client_AdsNotification2(object sender, AdsNotificationEventArgs e)
{
    // Or here we know about UDINT type --> can be marshalled as UINT32
    uint nCounter = BinaryPrimitives.ReadUInt32LittleEndian(e.Data.Span);

    // If Synchronization is needed (e.g. in Windows.Forms or WPF applications)
    // we could synchronize via SynchronizationContext into the UI Thread

    /*SynchronizationContext syncContext = SynchronizationContext.Current;
      _context.Post(status => someLabel.Text = nCounter.ToString(), null); // Non-blocking post */
}

Reference

AdsConnection Class

TwinCAT.Ads Namespace