Blocks For F Communication Between Cpus - Siemens SIMATIC S7 F Manual

Fail-Safe Blocks
8.3

Blocks for F Communication Between CPUs

To ensure additional safety-related data exchange between Safety Programs on
different CPUs, additional fail-safety-related information is also transferred as well
as the actual user data. This information and the associated mechanisms remain
hidden to the user.
The following blocks are available for F communication:
Block
F_SENDBO
F_RCVBO
F_SENDR
F_RCVR
ID and R_ID Addressing Parameters for F Communication Blocks
•
ID is the reference to the local connection description. ID is assigned during
connection configuration (NetPro). The I/O ID must be assigned parameters on
the sending side (F_SENDBO, F_SENDR) and on the receiving side
(F_RCVBO, F_RCVR).
•
Via R_ID you can define that a sending and a receiving fail-safe block belong
together: The associated fail-safe blocks receive the same value for R_ID. The
value R_ID is a freely selectable odd number, but it must be unique for a
sending/receiving F block pair.
Note
The value R_ID + 1 is also assigned and must not be used.
TIMEOUT Parameter
All four blocks for F communication have the TIMEOUT parameter for vital-sign
monitoring of the communication between the CPUs. You can find out how to
calculate TIMEOUT in the section entitled "Configuring the Monitoring Times for
F/FH Systems".
Note
Data transfer takes place cyclically. It can only be guaranteed 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 configured monitoring time (TIMEOUT).
Fail-Safe Systems
A5E00085588-03
Description
Send F_BOOL data to another CPU
Receive F_BOOL data from another CPU
Send F_REAL data to another CPU
Receive F_REAL data from another CPU
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