7.1 General

OPC 10000-4 specifies the complete set of services. The services needed for the purpose of DataAccess are:

• The View service set and Query service set to detect DataItems, and their Properties.

• The Attribute service set to read or write Attributes and in particular the value Attribute.

• The MonitoredItem and Subscription service set to set up monitoring of DataItems and to receive data change notifications.