OPC UA Subscriber Documentation

Version: 5.0.0

Retrieved: 2025-10-09 15:16:08

OPC UA Subscriber

The module is used to setup grouped subscriptions to an OPC UA server with a specified interval. When data is changed in the OPC UA server a message is sent from the module with the new values.

This module is designed to be located at the beginning of a flow.

Settings

In the settings you specify the URL and credentials used for setting up subscriptions on an OPC UA server. The NodeIds that are subscribed to can be loaded from a resource, entered manually or updated dynamically through an input message. You can also specify the sample interval used for monitoring the NodeIds.

When using resources to specify NodeIds to subscribe to, additional properties can be attached to each NodeId. These additional properties can be used in other modules in the flow for example to filter out certain NodeIds, apply scaling of values or just to add additional metadata. See the example below and the documentation for more information on the resource format.

Credential

This module contains an option to select credentials to use in the module. All credentials supported by the module are presented in a drop-down.

Input - Additional Tags

The module does not need any input. However additional nodes can be subscribed to by sending a message to the module. This message should have an array of NodeIds assigned to the property opcuasubscriber.nodeIds. The format of the array is the same as for OPC UA resources, see the documentation.

The NodeIds subscribed to at any time will be a combination of any manually entered NodeIds, any resource and the latest list through an input message.

Input - Refresh

If needed you can send in a message to the module with the property opcuasubscriber.refresh set to true. The module will then send out all values for the subscriptions (both from settings and from the opcuasubscriber.nodeIds if available).

Output

Each change of the value of a NodeId in the subscription will be individually sent out from the module into the next module(s).

Examples

Subscribing values from one NodeId from an OPC UA server.

# Settings:
Target Property = data
Server URL = opc.tcp://192.168.0.103:51210/UA/SampleServer
Tags collection (Resource) =
Additional tags to monitor =
  Name = CC2001_ControlOut, Node Id = ns=5;i=29
Publish Interval = 1 second
Include Display Name = true
Include Browse Name = true
Security Mode = None
Security Policy = None

# Outgoing message:
{
  "data": {
    "displayName": "ControlOut",
    "browserName": "4:ControlOut",
    "name": "CC2001_ControlOut",
    "dataType": "double",
    "nodeId": "29",
    "statusCode": "good",
    "sourceTimestamp": "2018-12-21T08:14:23.6567987Z",
    "value": 0.057499999999999996
  },
  "crosser": {
    "success": true
  }
}

Adding subscriptions by sending message to the module.

# Settings:
Target Property = data
Server URL = opc.tcp://192.168.0.103:51210/UA/SampleServer
Tags collection (Resource) =
Additional tags to monitor =
  Name = CC2001_ControlOut, Node Id = ns=5;i=29
Publish Interval = 1 second
Include Display Name = false
Include Browse Name = false
Security Mode = None
Security Policy = None

# Incoming message:
{
  "opcuasubscriber":{
    "nodeIds": [
      {
        "nodeId": "ns=3;i=1003",
        "name": "Sawtooth",
        "additionalData": {
          "a": 1,
          "b": true
        }
      }
    ]
  }
}

# Outgoing message:
{
  "data":  {
    "nodeId": "ns=3;i=1003",
    "name": "Sawtooth",
    "additionalData": {
      "a": 1,
      "b": true
    }
    "index": 2,
    "dataType": "Double",
    "statusCode": "Good",
    "sourceTimestamp": "2021-05-10T15:08:49Z",
    "value": -0.4
  },
  "crosser": {
    "success": true
  }
}