Alarm, fault and system messages
11.4 I/O device diagnostics
SIMATIC MV420 / SIMATIC MV440
Operating Instructions, 04/2013, A5E02371045-06
347
11.4 I/O device diagnostics
11.4.1 Introduction
Errors, for example, "Error - transfer error PROFINET IO", trigger I/O device diagnostics. The
diagnostic information is read out using STEP 7 depending on the I/O controller.
How to read out I/O device diagnostic information and how it is structured is described briefly
below. You will find a detailed description in the programming manual PROFINET IO – From
PROFIBUS DP to PROFINET IO.
11.4.2 Reading out diagnostics information with S7
If, for example, the error "Error - transfer error PROFINET IO" occurs on the reader and you
are using an S7 CPU as the I/O controller, the diagnostics interrupt OB (OB82) is started on
the I/O controller.
Its local variables OB_82_EV_CLASS, OB_82_MDL_DEFECT and OB82_EXT_FAULT have
the following values:
Variable Value Meaning
OB_82_EV_CLASS B#16#39 Event entering state
OB_82_MDL_DEFECT TRUE Module problem
OB_82_EXT_FAULT TRUE External problem
Unfortunately, you cannot identify the actual cause of the problem in the local variables of
OB82. You can find this out as follows:
● With PROFINET IO: By calling SFB 54 "RALRM" in OB 82
The entry "Faulty module" appears in the diagnostics buffer and the corresponding text from
the GSD file, for example "Error - transfer error PROFINET IO", appears in the module
information of the reader.
After the error has been eliminated and you have acknowledged it in the user interface of the
reader, the diagnostics interrupt OB (OB82) is started again on the I/O controller.
Its local variables OB_82_EV_CLASS, OB_82_MDL_DEFECT and OB82_EXT_FAULT have
the following values:
Variable Value Meaning
OB_82_EV_CLASS B#16#38 Event exiting state
OB_82_MDL_DEFECT FALSE No module problem
OB_82_EXT_FAULT FALSE No external problem
The entry "Module OK" now appears in the diagnostics buffer. The text from the GSD file
relating to the previous error no longer appears in the module information of the reader.
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