Siemens Simatic S7-400

Diagnostic data of signal modules
B
B.1 Evaluating diagnostic data of signal modules in the user program
This section
This section describes the diagnostic data structure in system data. You must be familiar with
this configuration if you want to evaluate the diagnostic data of the signal module in the STEP
7 user program.
Diagnostic data stored in data records
Module diagnostic data may have a length of max. 43 bytes, and are contained in data records
0 and 1:
● Data record 0 contains 4 bytes of diagnostic data describing the current state of an
automation system.
● Data record 1 contains the 4 bytes of diagnostic data that are also contained in data record
0 and as many as 39 bytes of module specific diagnostic data.
Further references
An in-depth description of the principle of evaluating the diagnostic data of signal modules in
the user program and a description of the SFCs that can be used for that purpose will be found
in the STEP 7 manuals.
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08 405