Siemens SIMATIC S7 Configuration And Programming Manual page 34

Procedure for Programming User Acknowledgment by Means of an
Acknowledgment Key at an F-I/O with Inputs that is Assigned to the F-CPU of the
DP Master
1. Call the F-application block F_SENDDP in the safety program in the F-CPU of
the DP master
(see manual, Section 5.4).
2. Call the F-application block F_RCVDP in the safety program in the F-CPU of
the intelligent DP slave (see manual, Section 5.4).
3. Supply an input SD_BO_xx of the F_SENDDP block with the input of the
acknowledgment key.
4. The acknowledgment signal for evaluating user acknowledgments is now
available at the corresponding output RD_BO_xx of the F_RCVDP block.
The acknowledgment signal can now be read in the program sections in which
further processing is to take place with fully qualified access directly in the
associated instance DB (for example, "Name F_RCVDP1".RD_BO_02). To
enable this, you must first assign a symbolic name (Name F_RCVDP1" in the
example) for the instance DB of F_RCVDP in the symbol table.
5. Supply the corresponding input SUBBO_xx of the F_RCVDP block with the
fail-safe value "RLO0," so that an unintended user acknowledgment is not
triggered before communication is established the first time after startup of the
sending and receiving F-system, or in the event of a safety-related
communication error. RLO 0 is provided in the F-Shared DB. At input
SUBBO_xx, enter "F_GLOBDB".RLO0 fully qualified.
Note
If a communication error/F-I/O fault, or channel fault occurs in the F-I/O to which
the acknowledgment button is connected, it is no longer possible to acknowledge
to reinclude this F-I/O.
This "block" can only be removed by a STOP/RUN change of the F-CPU of the
DP master.
To allow acknowledgment and reinclusion of an F-I/O to which an
acknowledgment button is connected, it is advisable to plan a further
acknowledgment over an operator control and monitoring system with which you
can access the F-CPU of the DP master (see manual, Section 5.3.9).
If a safety-related master to I-slave communication error occurs, the
acknowledgment signal cannot be transferred, and an acknowledgment for
reinclusion in the safety-related communication is no longer possible.
This "block" can only be removed by a STOP/RUN transition of the F-CPU of the
intelligent DP slave.
To allow acknowledgment and reinclusion in safety-related communication, it is
therefore advisable to plan a further acknowledgment over an operator control and
monitoring system, with which you can access the F-CPU of the I-slave and
transfer an acknowledgment signal (see 1.).
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