The variable of the OPC UA integration module is created on the basis of the group of items after you download the configuration.

To configure the variable of the OPC UA integration module, do the following:

1. Go to the settings panel of a variable.
   
2. Set the Monitor checkbox to ensure that the events of value change of the variable are included in the Event Viewer. By default, the checkbox is clear.
3. In the PublishingInterval (ms) field, specify in milliseconds the time interval between notifications about changes in the values of the variable that the server sends to the client. The default value is 1000. It means that the client receives data every second. You must select the value empirically.
   

   A shorter interval increases the rate of data update but also increases the load on the network and CPU. A longer interval reduces the load on the network and CPU but also delays the rate of data update.

4. In the SamplingInterval (ms) field, specify in milliseconds the time interval between polling or checking the values of the numeric variable on the device or in the data source. The default value is 1000. It means that the server requests data from the source, such as a sensor or controller, every second. You must select the value empirically.
   

   A shorter interval allows detecting changes faster but increases the load on the data source. A longer interval reduces the load on the data source, but it can miss fast changes in the values of the variable.

5. In the Queue size field, specify the number of stored changes of values of the variable between sent notifications if the client doesn't have time to process them. The default value is 3.
   

   When the queue is filled, the server can discard old values of the variable (if you set the Discard old value checkbox) or generate an error. If the queue size increases, more data is saved, but it requires more storage capacity.

6. Set the Discard old value checkbox to delete old values when the queue is filled. By default, the checkbox is clear.
7. In the Activation value field, specify the variable value that changes the states of the variable from Normal to Active. For example, when using variables of boolean type, you can set the value to true and monitor the state of the sensor connected to the OPC server on the map.
8. Click the Apply button to save the settings.
   

   The SamplingInterval (ms), Queue size, and Discard old value parameters are settings of the OPC server. If you cannot change these parameters of the OPC server, or these parameters don't exist at all, they don't work. For more information, see the documentation of the OPC server that you use.

Configuration of the variable of the OPC UA integration module is complete.