Siemens SIMATIC ET 200pro Operating Instructions Manual page 151

Glossary
PROFINET IO controller
Device used to address connected I/O devices (e.g. distributed I/O systems). This means
that: The IO controller exchanges input and output signals with assigned I/O devices. Often,
the IO controller is the CPU on which the automation program runs.
Real-time
Real-time means that a system processes external events within a defined time.
Determinism means that a system responds in a predictable (deterministic) manner.
Both requirements are important for industrial networks. PROFINET satisfies these
requirements. PROFINET is a deterministic real-time network by virtue of the following:
● Transmission of time-critical data between different stations over a network in a defined
time interval is guaranteed. For this, PROFINET provides an optimized communication
channel for real-time communication: Real-time (RT)
● An exact determination (forecast) of the transmission time instant is possible.
● It is ensured that smooth communication can take place in the same network using other
standard protocols, e.g. industrial communication for PG/PC.
Restart
During a warm restart, all non-retentive bit memory is deleted and non-retentive DB contents
are reset 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.
Retentivity
A memory area whose content is retained after power failure and after a STOP to RUN
transition is retentive. The non-retentive area of the bit memory, timers and counters is reset
after power failure and after a STOP to RUN transition.
Runtime error
Error that occurs during execution of the user program in the automation system (thus not in
the process).
SELV
Safety Extra Low Voltage = Safety extra-low voltage
Sensors
Encoders are used for exact acquisition of digital and analog signals and for measurement of
distances, positions, velocities, rotational speeds, masses, etc.
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CPU 1516pro-2 PN (6ES7516-2PN00-0AB0)
Operating Instructions, 11/2019, A5E35873416-AC