Siemens SIMATIC S7 F, Manual

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Fail-Safe Blocks
Fail-Safe Systems
8-22
A5E00085588-03
8.2.4 Common Features of the Driver Blocks
F Module Drivers
Safety frame
Fail-safe data exchange between a Safety Program and an F-I/O occurs via safety
frames. In addition to user data (i.e. process values), information on safety is also
transferred.
Monitoring Time TIMEOUT
See "Configuring the Monitoring Times for F/FH Systems".
Redundancy
The driver blocks support the following types of redundancy:
•
Signal redundancy in the case of digital input modules as a result of 1oo2
sensor evaluation: If a digital input module is run with 1oo2 sensor evaluation,
only F channel drivers can be placed for channels 0 to 3 of the digital input
module SM 326; DI 8 x NAMUR and channels 0 to 11 of the SM 326; DI 24 x
DC 24 V.
•
Module redundancy: The F module drivers are able to address two redundant
signal modules.
The settings necessary for this are made when parameters are assigned to the
modules in HWCONFIG.
Module redundancy
The processing of redundant modules comprises the following functions:
•
In the case of problem-free operation:
- In the case of digital input modules, the input signals are ORed per
channel.
- In the case of digital output modules, the digital value at I/O I of the
channel driver is forwarded to both modules in parallel.
- In the case of analog input modules, the input signals of the module that is
available first after startup are forwarded to the F channel drivers.
•
If a fault occurs on one of the redundant channels:
- In the case of digital input modules and analog input modules, a
switchover takes place to the channel of the other module.
-
In the case of digital output modules, the substitute value 0 is sent to the
channel with the fault.