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The following components and functions are tested:
● Coupling of the central controllers
● Processor
● Internal memory of the CPU
● I/O bus
If the self-test detects an error, the fault-tolerant system tries to eliminate it or to suppress its
effects.
For detailed information on the self-test, refer to Chapter Self-test (Page 104).
System operation without Stop
To best meet the requirements of the process industry for system operation without Stop,
PCS 7 intercepts as many possible stop causes as possible. The PA-CPU 410 has been
enhanced such that, as a redundant system, it reaches the Run Redundant operating state
automatically on every occasion if possible. A change in the operating state is only possible
through an engineering system command. In addition, the Stop command is password-
protected. The diagnostic information always indicates the RUN switch position.
7.2.2
The system states of the fault-tolerant system
The system states of the fault-tolerant system result from the operating states of the two
CPUs. The term "system state" is used as a simplified term which identifies the concurrent
operating states of the two CPUs.
Example: Instead of "the master CPU is in RUN and the standby CPU is in LINK-UP mode"
we say "the fault-tolerant system is in link-up mode".
Overview of system states
The table below provides an overview of the possible states of the fault-tolerant system.
Table 7- 2
System states of the fault-tolerant
system
Stop
Startup
Single mode
Link-up
Update
CPU 410-5H Process Automation/CPU 410 SMART
System Manual, 10/2013, A5E32631667-AA
Operator controls and operating modes of the CPU 410-5H
Overview of system states of the fault-tolerant system
Operating states of the two CPUs
Master
STOP
STARTUP
RUN
RUN
RUN
7.2 System states of the redundant CPU 410-5H
Reserve
STOP, power off, DEFECTIVE
STOP, power off, DEFECTIVE, no
synchronization
STOP, ERROR-SEARCH, power off,
DEFECTIVE, no synchronization
STARTUP, LINK-UP
UPDATE
99
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