Siemens SIMATIC MV440 Operating Instructions Manual page 340

Alarm, fault and system messages
11.2 Reporting diagnostics information
Self-acknowledging connection errors
The following connection errors are self-acknowledging:
● Error - TCP communication
● Error - archiving/MMI communication
● Error - PROFINET IO error
As soon as the connection is re-established after an interruption, the reader exits the error
status and returns to the mode prior to the occurrence of the error, for example back to
processing mode.
The occurrence of these errors and their automatic acknowledgement are stored in the
diagnostic data records and are not overwritten by new errors.
If such entries exist, this is indicated on the user interface in the "Run" and
"Information/Statistics" tasks.
Note
PROFINET IO error/OB 86 not programmed
• The occurrence of a PROFINET IO error causes OB 86 (rack failure OB) to be called on
a SIMATIC S7 CPU.
• Unless you have programmed OB86, the CPU changes to STOP.
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SIMATIC MV420 / SIMATIC MV440
Operating Instructions, 04/2013, A5E02371045-06