The <Point Type> tab on the Forms of OPC UA Analog, Digital, String and Time points contains a Queue Parameters section. You use the properties in this section to define the queue parameters.
The Queue Parameters section contains the following properties:
- Queue Size—Use this field to specify the size of the notification queue that the OPC UA server is to maintain for this point. The default value is 2.
When Geo SCADA Expert requests the OPC UA server to start monitoring a point, the OPC UA server will respond with the actual value for Queue Size that the point is using. The actual value may differ from the configured values. You can ascertain the actual value that the point is using by viewing the Actual Queue Size, a status attribute that is included in the point's Status display.
- Discard Oldest—Use this check box to specify whether the oldest item in the server’s queue is to be discarded when the queue exceeds the value specified in the Queue Size property.
Select the check box if the oldest item in the server’s queue is to be discarded when the queue becomes full.
Clear the check box if the newest item in the server’s queue is to be discarded when the queue becomes full. This is the default setting.