Fail-Safe Blocks
Fail-Safe Systems
A5E00085588-03
8-15
Substitute Value
In the event of communication errors (PROFIsafe) or channel faults (e.g. wire
break), in the case of passivation and during a startup (cold or warm restart), the
substitute value 0 is made available for the associated F module driver
(F_M_DOx). 16#48 is output as the quality code (QUALITY), and the output QBAD
= 1 is set.
If the substitute value is not caused by passivation, the output PASS_OUT = 1 is
set as well to passivate other channels. In the event of an error, the output of the
substitute value has the highest priority.
Startup Characteristics
After a startup (cold restart or warm restart), communication must first be
established between the F module driver and the digital output module. In this time,
the substitute value 0 is output with the quality code (QUALITY) 16#48, and the
outputs QBAD = 1 and PASS_OUT = 1 are set as well. At ACK_REQ = 1 the
ACK_REI acknowledgement must follow, even if ACK_NEC = 0.
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.
Error Information in Diagnostic Buffer
Error Code (W#16#...) Description
75DAH
Error in the safety data format (error due to online modification
of the Safety Program or internal CPU fault)
Report Characteristics
The block has no reporting behavior.
See Also
Common Features of the Driver Blocks
Passivation and Reintegration
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