Request Of A Remote Client Failed - Siemens SIMATIC ET 200AL System Manual

Example
If an attempt is made to compromise communications (for example, by session hijacking,
man-in-the-middle attacks etc.), the server detects this via analysis.
9.3.7.5

Request of a remote client failed

S7-1500 CPUs as of firmware version V2.8 are able to create an entry in the diagnostic buffer
for the following events:
• Bad client requests (incorrect use)
• Service error occurred
• CPU-specific high limits of the OPC UA server were violated
Example of a faulty client request
For example, there is an incorrect request when a client addresses a node (tag) that does not
exist or if a resource is requested that does not exist.
In this case, the corresponding service that caused the fault is entered in the diagnostic buffer
and the corresponding session ID is also entered.
Service fault
If a service itself fails, the server returns a ServiceFault. In this case, the status code (Bad...)
and the according session ID are entered in the diagnostics buffer.
Example of limit violations
If a service request exceeds a CPU-specific limit, for example, number of sessions, number of
monitored items, number of subscriptions, etc., this diagnostics is entered in the diagnostics
buffer. Together with the message, it is indicated which limit has been violated.
Exception: If you summarize diagnostics and the message occurs frequently, the limit causing
the error is not entered. You receive general information that the supported configuration
limit has been violated.
Communication
Function Manual, 05/2021, A5E03735815-AJ
OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
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