Glossary - Siemens SIMATIC S7-400H System Manual

Glossary

1-out-of-2 system
See dual-channel fault-tolerant system
Comparison error
An error that may occur while memories are being compared on a fault-tolerant system.
Dual-channel fault-tolerant system
Fault-tolerant system with two central processing units
ERROR-SEARCH
An operating mode of the reserve CPU of a fault-tolerant system in which the CPU performs
a complete self-test.
Fail-safe systems
Fail-safe systems are characterized by the fact that, when certain failures occur, they remain
in a safe state or go directly to another safe state.
Fault-tolerant station
A fault-tolerant station containing two central processing units (master and reserve).
Fault-tolerant system
A fault-tolerant system consists of at least two central processing units (master and reserve).
The user program is processed identically in both the master and reserve CPUs.
Fault-tolerant systems
Fault-tolerant systems are designed to reduce production downtime. Availability can be
enhanced, for example, by means of component redundancy .
I/O, one-sided
We speak of a one-sided 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) module.
S7-400H
System Manual, 03/2012, A5E00267695-11
495