Siemens SIMATIC S7 F Manual page 255

Fail-Safe Blocks
Name
Outputs: DIAG_1
DIAG_2
PROFIsafe1
PROFIsafe2
SM1, SM2 – redundant modules
Error Information at the Output DIAG_1/2
DIAG_1
Byte 0
Bit 0: TIMEOUT error on SM1
Bit 1: Common error on SM1
Bit 2: CRC value/watchdog error on SM1
Bit 3: Reserved
Bit 4: TIMEOUT error on CPU
Bit 5: Watchdog error on CPU
Bit 6: Check value error (CRC) on CPU
Bit 7: Reserved
Byte 1
Reserved
Byte 2
Reserved
Byte 3
Reserved
Note
In byte 0 of DIAG_1/2, the most recent error information remains stored until a new
error occurs, even if the error has already gone.
Error Handling
In the event of an error that is critical to safety, the system function SFC F_CTRL
is called. This records the event in the Diagnostic Buffer and requests a switch to
the reserve CPU if the error occurred only on the master CPU. For non-redundant
systems or a common-cause error occurring in both CPUs, the shutdown logic can
be configured to either disable the erred F-run-time group or the entire Safety
Program.
Fail-Safe Systems
A5E00085588-03
Data Type Explanation
DWORD Diagnostic information for
SM1, see table below
DWORD Diagnostic information for
SM2, see table below
F_BOOL Identify failure on a specific
PROFIsafe bus
F_BOOL Identify failure on a specfic
PROFIsafe bus
DIAG_2
Byte 0
Bit 0: TIMEOUT error on SM2
Bit 1: Common error on SM2
Bit 2: CRC value/watchdog error on SM2
Bit 3: Reserved
Bit 4: TIMEOUT error on CPU
Bit 5: Watchdog error on CPU
Bit 6: Check value error (CRC) on CPU
Bit 7: Reserved
Byte 1
Reserved
Byte 2
Reserved
Byte 3
Reserved
Default
0
0
0
0
8-67