# OpcClient.DataChangeReceived Event

> Reference: Occurs when a monitored item of one of the Subscriptions of the OpcClient receives a data change notification which is not handled by the monitored item and not handled by its subscription.

<dl class="api-definition">
<dt>Type</dt>
<dd><a href="./">OpcClient</a></dd>
<dt>Namespace</dt>
<dd><a href="../namespaces/opc.uafx.client">Opc.UaFx.Client</a></dd>
<dt>Assembly</dt>
<dd>Opc.UaFx.Advanced.dll</dd>
<dt>Package</dt>
<dd>Opc.UaFx.Advanced v2.59.0</dd>
<dt>Members</dt>
<dd><a href="./members">OpcClient Members</a></dd>
<dt>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Occurs when a monitored item of one of the [Subscriptions](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/subscriptions) of the [OpcClient](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/) receives a data change notification which is not handled by the monitored item and not handled by its subscription.

<div class="api-signature" data-lang="csharp">

```csharp
public event OpcDataChangeReceivedEventHandler DataChangeReceived
```

</div>

<div class="api-signature" data-lang="vbnet">

```vbnet
Public Event DataChangeReceived As OpcDataChangeReceivedEventHandler
```

</div>

**Event type**

[OpcDataChangeReceivedEventHandler](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcdatachangereceivedeventhandler/)

**Remarks**

This event only occurs if a data change is not handled by the according [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#datachangereceived) handler and not handled by the [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#datachangereceived) handler of the [OpcSubscription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/) of the [OpcMonitoredItem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/) (see [Handled](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcdatachangereceivedeventargs/members#handled)).