Siemens SIMATIC Operating Instructions Manual page 164

Glossary
Availability
Availability is the probability that a system is functional at a specific point in time. It can be
increased by redundancy, for example, by using multiple -> sensors at the same measuring
point.
Backplane Bus
The backplane bus is a serial data bus via which the IM 154 interface module communicates
with the electronic modules/motor starters and the necessary voltage is supplied. The
connection between individual modules is established by means of the terminal modules.
Category
Category in accordance with EN 954-01
-> Fail-safe modules can be used in safety mode up to Category 4.
Channel Fault
A channel fault is a channel-specific fault, such as a wire break or a short circuit.
In the case of channel-level passivation, the affected channel is either automatically
reintegrated or the F-module must be removed and inserted after the fault has been
eliminated.
Channel Group
The channels of a module are grouped together into a channel group. Certain parameters in
STEP 7
Channel Number
Channel numbers are used to uniquely identify the inputs and outputs of a module and to
assign channel-specific diagnostic messages.
Channel-Level Passivation
When a -> channel fault occurs, either the relevant channel or the entire module is
passivated in this passivation method. In the event of a -> module fault, all channels of the ->
fail-safe module are passivated.
Configuring
Configuring involves a systematic arrangement of the individual modules of ET 200pro.
CRC
Cyclic Redundancy Check -> CRC signature
164
can only be assigned to channel groups and not to individual channels.
ET 200pro Distributed I/O System - Fail-Safe Modules
Operating Instructions, 05/2007, A5E00394073-02