OPC UA Read

R2026b

Read data from OPC UA server

Since R2024a

• 

OPC UA Read block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Industrial Communication Toolbox / OPC Unified Architecture

Description

The OPC UA Read block reads data from one or more nodes on an OPC Unified Architecture (UA) server. The block subscribes to the selected nodes and receives data changes asynchronously. At each sample time, the block outputs the most recent value received from the server.

The block outputs the values of the selected nodes as a Simulink^® bus signal. It optionally outputs the timestamps and the quality value associated with each node in separate outputs. The nodes that you select in the block can have different data types, which remain unchanged in the Simulink bus signal. The block outputs the timestamp as a serial date number (real-world time), or as the number of seconds from when you start simulating the model (simulation time).

Note

You must connect at least one OPC UA server to use the OPC UA Read block. You can create an OPC UA client using the OPC Configuration pane in the Configuration Parameters dialog box of the model. You must add at least one OPC UA Read or OPC UA Write block in the model to enable this pane. For more information, see Configure OPC UA Client in Simulink.

Examples

Get Started with OPC UA in Simulink

Read and write data to nodes available on an OPC Unified Architecture (UA) server using Simulink® blocks from Industrial Communication Toolbox™. You can connect to the server using a Simulink model that acts as an OPC UA client. You can perform read and write operations in the model using the OPC UA Read and OPC UA Write blocks.

• Since R2024a
• Open Live Script

Monitor Data Value and Quality of OPC UA Nodes in Simulink

Implement a dashboard showing instantaneous values and quality metrics related to specific OPC Unified Architecture (UA) nodes using Simulink® blocks from Industrial Communication Toolbox™.

• Since R2024a
• Open Live Script

Use OPC UA Data to Test Binary Distillation Column Plant Model

Use data from an OPC UA server to test composition control of a binary distillation column model.

• Since R2024a
• Open Live Script

Ports

Output

Value — Current data values of selected nodes

scalar | bus

The block outputs the values of the selected nodes as one of these:

• A scalar Simulink signal when you select a single node. The signal has the same data type as the selected node.

• A Simulink bus signal when you select multiple nodes. Each signal in the bus inherits the data type of its corresponding node. Extract the value of a node from the Simulink bus signal using a Bus Selector (Simulink) block.

For more information on the data types supported at the Value port, see OPC UA Server Data Types.

Dependencies

To enable this port, specify one or more nodes in the Nodes parameter.

Data Types: Boolean | single | double | datetime | int8 | int16 | int32 | int64 | uint8 | uint8 vector | uint16 | uint32 | uint64 | struct | char vector | bus

Timestamp — Timestamp of selected nodes data

seconds (default) | date number

The block outputs the timestamp of the selected nodes data as one of these values:

• Seconds since start (default): Represents the simulation time at which the Simulink client received data from the server.

• Serial date number: Represents the real-world time at which the source provided data to the server.

Dependencies

To enable this port, select the Show timestamp port parameter.

Data Types: double

Quality — Quality of read data from selected nodes

boolean

The block outputs the quality of read data from selected nodes as Boolean values. A logical 0 output indicates 'Bad' or 'Uncertain' quality and logical 1 indicates 'Good' quality.

Dependencies

To enable this port, select the Show quality port parameter.

Data Types: Boolean

Parameters

Server — Define OPC UA server for block

drop-down list

Select the OPC UA client to associate with the block.

• To add the required clients using the OPC configuration pane, click Configure servers. For more information, see Configure OPC UA Client in Simulink.

• To update the block to the latest OPC configuration, click Refresh.

Programmatic Use

Block Parameter: ServerList

Type: string | character vector

Nodes — List of OPC UA server nodes

table

Select nodes to read from the specified server.

• To add variable type nodes, click Add. This action opens the Browse Namespace dialog box for the selected OPC UA server. Using this browser, you can select the nodes that you want to add to the Nodes list.

• To delete selected nodes, click Delete.

• To change the order of the selected nodes in the list, click Move Up or Move Down. The serial number of the nodes determines the order in which the block outputs the signals in the bus at the Value port.

Programmatic Use

Block Parameter: NodeList

Type: string | character vector

Show quality port — Add quality output to block

on (default) | off

When you select this parameter, the block outputs the quality of the read data at the Quality port, as a Boolean value. A quality value of 'Good' is indicated by logical 1 and a value of either 'Bad' or 'Uncertain' is indicated by a logical 0.

Programmatic Use

Block Parameter: ShowQualityPort

Type: string | character vector

Values: 'on' | 'off'

Default: 'on'

Show timestamp port — Add timestamp output to block

on (default) | off

When you select this parameter, the block outputs the timestamps of the selected nodes data at the Timestamp port, as a vector of doubles. You can select the timestamp basis using the Show timestamp port as parameter.

Programmatic Use

Block Parameter: ShowTimestampPort

Type: string | character vector

Values: 'on' | 'off'

Default: 'on'

Show timestamp port as — Set timestamp basis

Seconds since start (default) | Serial date number

Set the timestamp basis as Seconds since start or Serial date number.

Programmatic Use

Block Parameter: ShowTimestampPortAs

Type: string | character vector

Values: 'Seconds since start' | 'Serial date number'

Default: 'Seconds since start'

Sample time — Sample time for read operation

-1 (default) | nonnegative scalar

Define the sample time of the block in seconds. The sample time controls how often the block updates its output. The block outputs the most recent subscription data at the specified sample time. For more information, see Specify Sample Time (Simulink).

Programmatic Use

Block Parameter: SampleTime

Type: string | character vector

Values: '-1' | nonnegative scalar

Default: '-1'

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"opcualib/OPC UA Read"

Example: add_block("opcualib/OPC UA Read","myModel/myBlock",MakeNameUnique="on")

Version History

Introduced in R2024a

R2026b: Automatic session recovery

The MATLAB^® OPC UA client now automatically recovers disrupted sessions. The client reconnects and resumes operations without manual intervention. Simulation continues to run during temporary network interruptions.

R2026b: Subscription-based data acquisition

The OPC UA Read block now uses an OPC UA subscription instead of performing a synchronous read at every sample time.