Fail-Safe Systems
A5E00085588-03
2-1
2 Getting Started
2.1 Introduction
This introduction uses concrete examples to walk you through the steps required to
create a working application, which will enable you to discover how a fail-safe
automation system works, and how it behaves in the event of a fault/error.
The following two systems will be used as examples to lead you through the initial
commissioning phase to an actual working application.
• A fail-safe, S7 F system, and
• A fail-safe, fault-tolerant S7 FH system
Terminology
The following table describes terminology used in the example projects.
F_SHUTDN A standard function block used to manage the shutdown and
restart of the Safety Program. Please see chapter 8 for more
information on the F_SHUTDN function block.
F-run-time
group
This is a run-time group that has F-Blocks within it. The Step 7
definition of run-time groups: (Run-time groups are used to
structure tasks. The blocks are installed sequentially in the run-
time groups. Run-time groups can be activated and deactivated
separately. If a run-time group is deactivated, the blocks it
contains will no longer be activated.)
Safety
Program
This is the collection of all F-run-time groups within the project.
Force Full
Shutdown
The user may force the manual shutdown of the entire Safety
Program through the RQ_FULL input of the F_SHUTDN function
block.
Full
Shutdown
The Shutdown logic responds to an internal diagnostic that has
detected a failure by disabling the entire Safety Program (Please
note that CPU will remaining running). This is configured on the
F_SHUTDN SHUTDOWN input.
Partial
Shutdown
The Shutdown logic responds to an internal diagnostic that has
detected a failure by disabling only that F-run-time group that
encountered the failure (Please note that CPU will remain
running). This is configured on the F_SHUTDN SHUTDOWN
input.
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