Glossary - Siemens SIMATIC S7-400H Manual

Glossary

1–out–of–2 system
See Dual–channel H system
Comparison error
An error that may occur while memories are being compared on a fault–tolerant
system.
Dual–channel H system
H system with two central modules
Fail–safe systems
Fail–safe systems are characterized by the fact that they remain in a safe state
when certain failures occur or go directly to another safe state.
Fault-tolerant systems
Fault–tolerant systems are designed to reduce production downtime. Availability
can be enhanced, for example, by means of component redundancy.
H station
A station containing two central processing units (master and standby).
H system
Fault–tolerant system consisting of at least two central processing units (master
and standby). The user program is processed identically in both the master and
standby CPUs.
I/O, one–way
We speak of a one–way I/O when an input/output module can be accessed by
only one of the redundant central processing units. It may be single–channel or
multi–channel (redundant).
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
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