Siemens SIMATIC S7 F, Manual

Page: 177 / 354

Safety
Fail-Safe Systems
A5E00085588-03
7-11
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) +
TSLAVE_SO + 2* TDP_DLY
Note the following:
Time Description Where to Find it?
TCI Configured cycle time of
the cyclic interrupt OB HWCONFIG
CPU properties, "Cyclic Interrupt,
Execution"
TCImax Maximum cycle time of the
relevant cyclic interrupt OB Monitoring the F Cycle Time section
TTR Max. target rotation time
for the DP master system Properties of the DP master system,
bus parameters in HWCONFIG
TDP_FD Max. DP fault detection
time Properties of the DP master system,
bus parameters, "H Parameters" tab
in HWCONFIG
TDP_SO Max. DP switchover time Properties of the DP master system,
bus parameters, "H Parameters" tab
in HWCONFIG
TSLAVE_SO Maximum switchover time
for the active
communication channel in
a switched I/O system In the technical specifications of the
switched DP slave (ET 200M)
TF-I/O, ACK Maximum acknowledgment
time of the F-I/Oin safety
mode You can find this time in the technical
specifications of the fail-safe I/O
manuals.
TDP_DLY Additional DP Delay Time,
External DP Interface (DP) Properties of the External DP
Interface (CP), “Operating Mode tab in
HWCONFIG.