F_Cyc_Co; Pd_Flag Not To Be Interconnected - Siemens SIMATIC S7 F Manual

Fail-Safe Blocks
8.6.1

F_CYC_CO

Function
This block monitors the cycle time of its priority class (cyclic interrupt OB 3x) and
provides a fail-safe time base for other F blocks.
At compilation, the block is inserted automatically into a F-run-time group named
@F_CycCo-OB3x, where x is 0 through 8 that correspond to the OB3x containing
F-Blocks, that contain the blocks F_TESTC and F_TEST.
If the value of MAX_CYC is invalid, a new value will be requested at compile time.
See "Configuring the Monitoring Times for F/FH Systems".
Safety Note – PD_FLAG not to be interconnected
!
The invisible output PD_FLAG must not be interconnected.
I/Os
Name
Inputs:
MAX_CYC
PD OFF
Outputs: PD FLAG
DIFF
CYC_SQ
FAILED
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.
8-56
Data Type Explanation
F_TIME Maximum permissible
F cycle time
F_BOOL Power Down Monitoring
F_BOOL Power-off code
F_DINT Time difference since the last
cycle in ms
F_INT Sequence number
BOOL Failure of the OB Indicator
Default
T# 0s
0
0
0
0
0
Fail-Safe Systems
A5E00085588-03