Siemens SIMATIC ET 200AL, System Manual

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OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
Communication
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Function Manual, 05/2021, A5E03735815-AJ
Methods for OPC UA Alarms and Conditions
In the following, the methods are briefly explained with the special features and restrictions
caused by the implementation for the OPC UA server of the S7-1500 CPU.
The methods are visible in the type space.
The OPC UA specification listed above contains the general description.
You can find a detailed description of the individual methods below this overview table.
Method Description
Acknowledge Method for acknowledging an alarm object that is uniquely
identified by a EventId.
ConditionRefresh Method for requesting an update of all alarm objects (in
SIMATIC language: updating of all pending alarms). All mon-
itored items of the subscription are updated.
Synchronization of pending alarm objects from the OPC UA
server of the CPU is indicated e.g. in the following situa-
tions:
•
Connecting for the first time or resuming the connection
(after interrupting the communication)
• Screen change on an operator screen of an HMI device
AddComment Method for adding comments to alarm objects.
Calling the "Acknowledge" and "AddComment" methods
Method calls in OPC UA use MethodId and ObjectId.
In the case of an alarm object, ObjectId is the node ID for the instance of the alarm object.
Since the address model of Simatic Alarms and Conditions does not provide instances for
alarm objects, the OPC UA specification provides in this case that the OPC UA client uses the
ConditionId as ObjectId.
You can find information on how to determine the ConditionId using a
SimpleAttributeOperands in the SelectClause of the event filter, see also the OPC UA
specification Part 9 (OPC 10000-9: Alarms & Conditions):