Siemens SIMATIC S7 F Manual page 177

Safety
7.4.2.2 Monitoring Safety-Related Communication Between the F-CPU
and F-I/Os
PROFIsafe time monitoring is executed in the F-I/Oand F driver with the same
PROFIsafe monitoring time. The value is entered in HWCONFIG as the monitoring
time of the F-I/O and assigned (monitoring time) and automatically assigned to the
F drivers at compilation (TIMEOUT).
To ensure that monitoring is not triggered in either the F driver or the F-I/O when
there are no faults, the PROFIsafe monitoring time TPSTO selected must be
sufficiently long:
TPSTO > 2* TTR + TF-I/O, ACK + MAX(TCImax ; TCI + TDP_FD) + TDP_SO +
TSLAVE_SO + 2* TDP_DLY
Note the following:
Time
TCI
TCImax
TTR
TDP_FD
TDP_SO
TSLAVE_SO
TF-I/O, ACK
TDP_DLY
Fail-Safe Systems
A5E00085588-03
Description
Configured cycle time of
the cyclic interrupt OB
Maximum cycle time of the
relevant cyclic interrupt OB
Max. target rotation time
for the DP master system
Max. DP fault detection
time
Max. DP switchover time
Maximum switchover time
for the active
communication channel in
a switched I/O system
Maximum acknowledgment
time of the F-I/Oin safety
mode
Additional DP Delay Time,
External DP Interface (DP)
Where to Find it?
HWCONFIG
CPU properties, "Cyclic Interrupt,
Execution"
Monitoring the F Cycle Time section
Properties of the DP master system,
bus parameters in HWCONFIG
Properties of the DP master system,
bus parameters, "H Parameters" tab
in HWCONFIG
Properties of the DP master system,
bus parameters, "H Parameters" tab
in HWCONFIG
In the technical specifications of the
switched DP slave (ET 200M)
You can find this time in the technical
specifications of the fail-safe I/O
manuals.
Properties of the External DP
Interface (CP), "Operating Mode tab in
HWCONFIG.
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