Configurations and Help with Selection
2.3 Configuration Variants for Fail-safe Systems According to Availability Requirements
2.3
Configuration Variants for Fail-safe Systems According to
Availability Requirements
Options for Increasing Availability
To increase availability of an automation system and, thus, to prevent process failures due to
faults in the F-system, S7 F Systems fail-safe systems can be configured optionally as faulttolerant systems (S7 FH Systems). This increased availability can be achieved by
component redundancy (F-CPU, communication connections, and F-I/O).
For S7 F Systems, availability can be increased without fault-tolerant configuration. Fail-safe
signal modules (F-SMs) can be used redundantly in one ET 200M or in several ET 200Ms.
The following section includes a description of how to achieve increased availability through
redundancy of the F-CPU and F-I/O in S7 FH Systems.
Note
Availability of the fail-safe CPUs in S7 Distributed Safety and S7 F Systems cannot be
increased by using the "SW Redundancy" software package.
Configuration Options in Safety Mode
Fail-safe systems can be configured three different ways, as follows:
Table 2- 1
Configuration Options for Fail-safe Systems According to Availability
System
S7
Distributed
Safety
Configuration
Option
Description
Availability
•
Single-channel
I/O
Single-channel and fail-safe (F-CPU and F-I/O Standard
are not redundant)
availability
•
Single-channel
switched I/O
Single-channel switched and fail-safe (F-CPU
is redundant, F-I/O is not redundant; in the
event of a fault, the system switches over to
the other F-CPU)
•
Redundant
switched I/O
Multichannel and fail-safe (F-CPU, PROFIBUS Highest
DP, and F-I/O are redundant)
availability
S7 F
Systems
S7 FH
Systems
Increased
availability
Typical configuration examples are presented below. A different level of availability of
process data is achieved for each configuration variant.
Safety Engineering in SIMATIC S7
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System Manual, 07/2013, A5E00109529-07