Siemens SIMATIC ET 200AL System Manual page 131

Channel
In IEC 61508 terminology, a channel is a single signal/logic path that supports a safety
function. The term 'channel' is used in this sense in the definition of 1oo1 and 1oo2 above. In
most cases in this manual, the term 'channel' refers to exactly one process value, which may
be implemented as 1oo1 or 1oo2.
Channel fault
Channel-specific fault, such as a wire break or short circuit.
In channel-specific passivation, the affected channel is either automatically reintegrated or
the fail-safe module must be removed and reinserted after the fault has been eliminated.
Channel group
The channels of a module are grouped together in a channel group. Certain parameters in
STEP 7 can only be assigned to channel groups, rather than to individual channels.
Channel number
Channel numbers are used to uniquely identify the inputs and outputs of a module and to
assign channel-specific diagnostic messages.
Channel-specific passivation
With this type of passivation, only the affected channel is passivated in the event of a →
channel fault. In the event of a → module fault, all channels of the → fail-safe module are
passivated.
Configuration
Systematic arrangement of individual modules (design).
Connection plug
Physical connection between device and cable.
CRC
Cyclic Redundancy Check
CRC signature
The validity of the process values in the safety frame, the accuracy of the assigned address
references, and the safety-related parameters are validated by means of the CRC signature in
the safety frame.
Distributed I/O system
System Manual, 08/2021, A5E31861578-AJ
Glossary
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