---
title: OPC UA
slug: bhdo-v2/opc-ua
createdAt: 2022-07-04T20:49:58.000Z
---
:::hint{type="info"}
**NOTE**: If the server is running on Windows, make sure to add the Domain name to the list of local hosts. See the *Hosts File* section in [Configure DNS/NTP Servers](docId\:vA-HuNwqw6p_PZeX9WxO1) for more information.
:::
Here are the major differences for the OPC UA Client drivers:
| **This driver** | **Does this** |
| ------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [DeviceHub Agent](docId\:W1rt2YXvLrQieLaMOq625) | - Connects to the Belden Horizon Data Operations DeviceHub Agent, which forwards data from an OPC Classic (Data Access) Server. |
| [OPC UA Client Advanced](docId\:r2V6FCTf3WB276nQPQm5m) | - Recommended driver to use to connect to an OPC UA Server.
- Has subscribe and polling modes. |
| [OPC UA Client](docId\:DZ6KgS6CAmnLTMtRH8zFE) | - Used to subscribe data from OPC UA servers.
- Only sends a message to the broker if the value changes at the server level.
- Subscription interval is defined at the driver level and does not have a polling interval at the tag level. |
| [OPC UA Client Poll](docId\:VPIX0nxX8SU1trCVnap2R) | - Polls the OPC UA server at regular user-defined intervals, returning the latest status from all specified nodes.
- As soon as a record is generated, the status is passed to the pipeline to avoid delays in processing. |