Siemens SIMATIC S7-1500 System Manual page 384

Glossary
Reference potential
Potential from which the voltages of the circuits involved are observed and/or measured.
Restart
A warm restart deletes all non-retentive bit memory and resets non-retentive DB contents to
the initial values from load memory. Retentive bit memory and retentive DB contents are
retained. Program execution begins at the call of the first startup OB. A restart is triggered
with CPU POWER OFF/POWER ON.
Retentivity
A memory area whose content is retained after power failure and after a STOP to RUN
transition is retentive. The non-retentive area bit memory area, timers and counters are reset
after a power failure and after a STOP to RUN transition. The non-retentive content of data
blocks is reset to the initial values.
Row
All the modules attached to a mounting rail.
Runtime error
Error that occurs during execution of the user program in the automation system (thus not in
the process).
Safety class
Safety level (Safety Integrity Level) SIL according to IEC 61508. The greater the Safety
Integrity Level, the stronger the measures for preventing system errors as well as for control
of system errors and hardware failures.
With the fail-safe modules, use up to safety class SIL3 is possible.
Safety function
Mechanism integrated in F-CPU and F-I/O that enables use in the SIMATIC Safety fail-safe
system.
According to IEC 61508: Function that is implemented by a safety relay to keep the system in
the safe state in case of a specific error or to bring it into a safe state.
Safety program
Safety-oriented user program
SELV
Safety Extra Low Voltage = Safety extra-low voltage
SNMP
SNMP (Simple Network Management Protocol) is the standardized protocol for performing
diagnostics on and assigning parameters to the Ethernet network infrastructure.
384
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD