Siemens SIMATIC ET 200SP System Manual page 304

Glossary
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.
Crimping
Procedure in which two components, e.g. end sleeve and cable, are connected with each
other by plastic strain.
Dark period
Dark periods occur during shutdown tests and complete bit pattern tests. The fail-safe output
module switches test-related zero signals to the active output. This output is then briefly
disabled (= dark period). An adequate carrier → actuator will not respond to this and will
remain activated.
Derating
Derating allows devices to be used even in harsh operating conditions by selectively
restricting the output capacity. In the case of motor starters, this usually refers to operation at
high ambient temperatures.
Device name
Before an IO device can be addressed by an IO controller, it must have a device name.
An IO device is delivered without a device name. An IO device can only be addressed by the
IO controller after it has been assigned a device name via the PG/PC or via the topology,
e.g. for the transfer of configuration data (such as IP address) during startup or for the
exchange of user data during cyclic operation.
Diagnostics
Monitoring functions for the recognition, localization, classification, display and further
evaluation of errors, faults and alarms. They run automatically during plant operation. This
increases the availability of plants because commissioning times and downtimes are
reduced.
Discrepancy analysis
The discrepancy analysis for equivalence/non-equivalence is used for fail-safe applications
to prevent errors from time differences between two signals for the same function. The
discrepancy analysis is initiated when different levels are detected in two associated input
signals (when testing for non-equivalence: the same levels). A check is performed to
determine whether the difference (for nonequivalence testing: the same levels) has
disappeared after an assignable time period, the so-called discrepancy time. If not, this
means that a discrepancy error exists.
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Distributed I/O system
System Manual, 09/2019, A5E03576849-AJ