Siemens SIMATIC RF166C, Operating Instructions Manual

Page: 116 / 176

Programming via OPC UA
9.3 OPC UA events
SIMATIC RF166C
116
Operating Instructions, 12/2019, C79000-G8976-C578-01
9.3 OPC UA events
9.3.1 Description of the events
OPC UA variables represent a simple way to query or accept information from the
communication modules.
The known difficulties in time-based synchronization between the query and update of the
variable values during more complex process with OPC UA variables do not occur with
events. If events are defined for specific actions, an independent event is generated for each
action that has occurred and been completed. Overwriting the related information is
excluded.
With events, in contrast to variables with their simple data types, OPC UA clients require the
possibility to handle more complex data types such as structures and unions in addition.
The integrated OPC UA servers of the communication modules offer the following three
additional events as a supplement to the AutoID standard:
● AutoIdPresenceEvent
● RfidLastAccessEvent
● AutoIdLastLogEntryEvent
These three events are for diagnostics purposes. These events are derived directly or
indirectly from the "AutoIdDiagnosisEvent" event, which in turn is derived from "BaseEvent"
with its properties as defined in the OPC UA standard.
Figure 9-3 Derivations of the OPC UA events based on the "BaseEvent"