Siemens SIMATIC S7 F, Manual

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Fail-Safe Blocks
Fail-Safe Systems
A5E00085588-03
8-127
8.13.12 F_SMP_AV
Function
This block outputs the mean value of the last N input values at the output.
OUT = (INk+INk-1+ ... +INk-N+1) / N
INk is the current input value.
The number N of input values must fulfill the condition 0 < N < 33.
I/Os
Name Data Type Explanation Default
Inputs: IN F_REAL Input variable 0.0
N F_INT Number of input variables
monitored 1
Outputs:
OUT F_REAL Mean value 0.0
Startup Characteristics
As long as N input values have not been read in after a cold or warm restart or in
the case of a first call, only the available input values (< N) are taken into account
for mean value formation. Input values saved before the startup are not taken into
account.
Error Handling
If the condition 0 < N < 33 is not fulfilled, OUT = INk is set.
If the operation generates an invalid REAL number the event will be recorded in
the Diagnostic Buffer.
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 of the IN input (error due to
online modification of the Safety Program or internal CPU
fault)
75D9H Invalid REAL number generated by the operation.