Siemens SIMATIC S7-1500 Function Manual page 243

OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
Subscription: Error in the sampling times
As of firmware V2.5 of the SIMATIC S7-1500 CPU, the OPC UA server can transmit the
status code "GoodOverload" when using subscriptions, if an overload of the CPU occurs
when sampling the items.
As of firmware V2.8 of the SIMATIC S7-1500 CPU, the OPC UA server can also enter this
event into the diagnostic buffer.
Requirement
In the OPC UA properties of the CPU, the option "Subscriptions: Sampling time errors"
(OPC UA > Server > Diagnostics) is selected.
Error-free subscription
In the case of an OPC UA subscription to various elements (such as tags), the OPC UA
server of the SIMATIC S7-1500 must check the elements for value changes at specified
intervals (sampling interval). This check, referred to as "sampling", requires some time,
which depends on the number and the data type of the items. After the sampling is
completed and a publishing request has been received, the server sends the elements to the
client.
Figure 9-51
242
Error-free subscription
Function Manual, 11/2019, A5E03735815-AH
Communication