---
title: OPC UA
slug: litmusedge-v2/quickstart-guide/industrial-systems-connection-guide/opc-ua
description: Review the different OPC UA DeviceHub drivers and what they do.
docTags:
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:7ST3zVQtdwC4J344LKqIO) for more information.
:::
Here are the major differences for the OPC UA Client drivers:
| **This driver** | **Does this** |
| ----------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| [DeviceHub Agent](docId:0CY_zbj3IkH5ikzeLqnxv) | Connects to the Litmus Edge DeviceHub Agent, which forwards data from an OPC Classic (Data Access) Server. |
| [OPC UA Client Advanced](docId:6B8E6ZXJPADP0MOPxQiQu) | - Recommended driver to use to connect to an OPC UA Server.
- Has subscribe and polling modes.
- Support OPC UA Alarms and Events. See [Use the OPC UA Client Advanced driver for OPC UA Alarms & Events](docId:4-oqkh6MtE4xUQkh_RxbK) for more details. |
| [OPC UA Client](docId\:jQEnJoYYqdsodSt8fvaRd) | - 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:3LqrhzX21QhL6SEjvb5r0) | - 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. |