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

  1. Go to the settings panel of the OPC UA Numeric variable object that is created automatically after you download the configuration on the basis of the Server OPC UA object (see Configuring the object of the Server OPC UA integration module).
  2. In the Discard old value field, select the True value to discard old values when the queue is filled. The default value is False.
  3. In the Max normal value field, specify the value of the numeric variable that causes an alarm when exceeded. For example, if the numeric variable can take values from 0 to 10, and the alarm occurs at 6, then in the Min normal value field, enter 0 and in the Max normal value field, enter 5.
  4. In the Min normal value field, specify the minimum allowable value of the numeric variable.
  5. In the Monitor field, select the True value if you want the events of value change of the numeric variable to be displayed on the Event Board (see Working with Event Boards). The default value is False.
  6. In the PublishingInterval (ms) field, specify in milliseconds the time interval between notifications about changes in numeric variable values 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. The value must be in the range [10, 60000]. 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.
  7. In the Queue size field, specify the number of stored changes of numeric variable values between sent notifications if the client doesn't have time to process them. The default value is 3. The value must be in the range [1, 50]. When the queue is filled, the server can discard old numeric variable values (if you select the True value in the Discard old value field) or generate an error. If the queue size increases, more data is saved, but it requires more storage capacity.
  8. In the SamplingInterval (ms) field, specify in milliseconds the time interval between polling or checking the numeric variable values 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. The value must be in the range [-1, 60000]. 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 numeric variable values.
  9. Click the Apply button to save the settings.

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

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