---
title: OPC UA Client Poll
slug: bhdo-v2/opc-ua-client-poll
createdAt: 2022-07-05T14:21:17.000Z
---

:::hint{type="info"}
**Note**: This driver will be deprecated in a future release. We recommend using [OPC UA Client Advanced](docId\:r2V6FCTf3WB276nQPQm5m).
:::

Review the following information for setting up and configuring the OPC UA Client Poll driver. 

# Belden Horizon Data Operations Compatible Series 

| Compatibility parameter        | Compatible items                                                                                                                                                                                                                |
| ------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Driver type**                | Ethernet                                                                                                                                                                                                                        |
| **Functionality&#x20;**        | - Polls the OPC UA server at regular user-defined intervals, returning the latest status from all specified nodes.<br />- As soon as a record is generated, the status is passed to the pipeline to avoid delays in processing. |
| **Replaced with Gen 2 driver** | [OPC UA Client Advanced](docId\:r2V6FCTf3WB276nQPQm5m)                                                                                                                                                                          |

# Supported Servers

## OPC UA Client

- It provides better performance compared to other OPC UA Clients.
- OPC UA Client with new design supports both poll and subscription mode.

# Set up the PLC Device in Belden Horizon Data Operations DeviceHub

Configure the following parameters when you [Connect a Device](docId\:T-cWPe0_Jsfw5-aoj8WPP) with this driver. Update default values to the specific setup of your device.&#x20;

| Parameter           | Value                 |
| ------------------- | --------------------- |
| **Type**            | OPC UA                |
| **Driver**          | OPC UA Client Poll    |
| **Network Address** | The device IP address |
| **Network Port**    | 4840                  |
| **Certificate**     | Auto-generated        |
| **Private Key**     | Auto-generated        |
| **Timeout Seconds** | 10                    |

# Configure the List of Registers

Browse for tags to add to this FreeTag device. See [Add Tags](docId\:PYRa8tUvdoIeJm1luBm-O) to learn more.&#x20;

Alternatively, when you [Add Tags](docId\:PYRa8tUvdoIeJm1luBm-O), for **Register Name** map the OPC server tags to the client using this format: `ns=1;s=tagname`.

Example: Example: `ns=2;s=Demo.Static.Scalar.Boolean`

The following data types are supported:&#x20;

- `int32`
- `bool`
- `sbyte`
- `byte`
- `int16`
- `uint16`
- `int32`
- `uint32`
- `int64`
- `uint64`
- `float32`
- `float64`
- `string`
- `dump`
- `desc`

Refer to the following tag parameters.&#x20;

## Tag Parameters

- **Name**: Enter a name based on this format: `ns=1;s=tagname`.
  - Example: `ns=2;s=Demo.Static.Scalar.Boolean`
- **Value Type**: Select a data type from the drop-down list.&#x20;
- **Polling Interval**: Enter a value in seconds. This determines how often the tag should poll the register for data.
- **Tag Name**: Enter a name for the tag.&#x20;
- **Description** (Optional): Enter a description for the tag. &#x20;
- **Tag Formula**: Enter a formula for the tag to process the generated data. Two variables are permitted: `value` (current tag value) and `timestamp` (current tag UNIX time in milliseconds). The following math functions are available:
  - sin
  - cos
  - sqrt
  - tan
  - power
  - log
  - exp
- **Only Publish on Change of Value**: Select the checkbox to customize NATS messages to be published only when the *value&#x20;*&#x70;arameter changes from a previous value to a new one. *Change of Value* only applies to boolean, numeric (such as int or float), and simple string data types. It does not apply to complex types, such as JSON or array. Poll-once topics will not be affected by *Change of Value* settings. These topics will still only see a single message.
- **Meta Data**: Metadata summarizes basic information about data. This feature allows you to define key-value pair data for the device output payload later on. It can then be used to find, use, and reuse particular instances of data.&#x20;