Siemens SIMATIC S7 F Manual page 47

Getting Started
Inserting F-Blocks
1. Close the Run Sequences either by closing the window within CFC editor, or
pressing Control-F11.
2. Insert user logic such as F_ADD_R, F_LIM_R etc... Refer to section Inserting
and Interconnecting Fail-Safe Blocks for details.
Note 1
The fail-safe blocks of the Failsafe Blocks library are yellow to differentiate them
from standard blocks.
Note 2
Previously a chart needed to be added manually by the user with the F_CYC_CO.
This is no longer necessary or allowed. The Placement of the F_CYC_CO blocks
is now a system function.
3. Insert two F_CH_DI F channel drivers to read in the fail-safe input module,
channels 0 and 1 (input value is at the Q output of the F_CH_DI FB).
4. Interconnect the VALUE input with the symbolic names for channel 0 (e.g.
E24.0) and channel 1 (e.g. E24.1) using the right mouse button and
Interconnection to Address.
5. Assign a value of 1 to the ACK_NEC input: in the event of an error, user
acknowledgment (at ACK_REI) is required for reintegration.
6. Place two F_CH_DO F channel drivers (values are at the I input) to write to the
fail-safe output module.
7. Interconnect the VALUE output with the symbolic name for channel 0 (e.g.
A.8.0) and channel 1 (e.g. A.8.1).
8. Assign the value 1 to the ACK_NEC input.
9. Connect the Q outputs of the two F_CH_DI with the I inputs of the
corresponding F_CH_DOs.
10. Insert the F_QUITES block (fail-safe acknowledgment) from the library and
connect the OUT output to the ACK_REI inputs of the two F_CH_DI and the
two F_CH_DOs.
Fail-Safe Systems
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