Siemens SIMATIC S7 F Manual page 319

Fail-Safe Blocks
Error Signaling
The following block outputs are activated:
•
DIAG_1, DIAG_2 at the F_M_xx F module drivers: diagnostic information for
the whole SM 1 or SM 2 module
•
QUALITY at the F_CH_xx F channel drivers: quality code of the process value
per channel
•
QBAD at the F_CH_xx F channel drivers: The output is set if substitute values
are output.
•
ACK_REQ at the F_CH_xx F channel drivers: The output is set if a user
acknowledgment is required.
You can find an overview of diagnostic messages and possible remedies in the
section entitled "Error Information at the Outputs of the Driver Blocks".
Error in the Safety Data Format
If an error is detected in the safety data format, the system function SFC F_CTRL
is called automatically. The system function SFC F_CTRL records the event in the
Diagnostic Buffer and requests a switch to the reserve CPU if the error occurred
only on the master CPU. By reading the Diagnostic Buffer you can find out:
•
The number of the fail-safe block that triggered the error.
•
An error code and thus the cause of the error.
The error codes and their causes are described for each of the fail-safe blocks.
See Also
Error Information at the Outputs of the Driver Blocks
Fail-Safe Systems
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