Siemens SIMATIC S7 F, Manual

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Programming
Fail-Safe Systems
5-32
A5E00085588-03
Procedure
Proceed as follows:
1. Insert the send block (F_SENDBO/F_SENDR) in the Safety Program from
which data is to be transferred.
2. Insert the receive block (F_RCVBO/F_RCVR) in the Safety Program to which
data is to be transferred.
3. Assign parameters to the ID inputs with the relevant identifiers of the
configured S7 connections.
4. Assign parameters to the R_ID inputs. This establishes that the send and
receive blocks belong together: The associated fail-safe blocks contain the
same (freely selectable, odd) value for R_ID. Note that the value R_ID+1 is
filled automatically when this happens.
5. Interconnect the SD_BO_xx and SD_R_xx inputs of the F_SENDBO and
F_SENDR F blocks with the send signals.
6. Interconnect the RD_BO_xx and RD_R_xx outputs of the F_RCVBO and
F_RCVR F blocks with the F-Blocks for further processing the receive signals.
7. Assign parameters to the TIMEOUT inputs of the send and receive blocks with
the desired monitoring time.
You can find information on how to calculate this in the section entitled
"Configuring the Monitoring Times for S7 F/FH Systems".
Note
It can only be guaranteed (with fail safety) that a signal level to be transferred will
be detected on the sender side and transferred to the recipient if it is present for at
least as long as the specified monitoring time (TIMEOUT).
8. Interconnect the ACK_NEC outputs of the F-blocks F_RCVBO and F_RCVR
to find out whether it is necessary to acknowledge reintegration after an error
has been eliminated.
9. Interconnect the relevant ACK_REI inputs of the F-blocks F_RCVBO F_RCVR
with the signal for the reintegration acknowledgment.
!
Safety Note – Safety Program must be re-compiled if S7 connections used
for CPU-CPU Communication have changed.
If the Safety Program contains blocks for safe CPU-CPU communication:
After a CPU has been copied or a program or chart has been copied to another
CPU, or after a communication partner of an S7 connection has been changed, the
program must be compiled again to update the connection data.