Siemens SIMATIC ET 200AL, System Manual

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Glossary
PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL
315
Backup CPU
If the R/H system is in RUN-Redundant system state, the primary CPU controls the process.
The backup CPU synchronously executes the user program and can take over the process
control on failure of the primary CPU.
Bus
A bus is a transfer medium that interconnects several devices. Data transmission can be
performed electrically or via optical fibers, either in series or in parallel.
Communications Cycle and Reservation of Transmission Bandwidth
PROFINET IO is a scalable real-time communication system based on the Layer 2 protocol for
Fast Ethernet. With the RT transmission method, two real-time-support performance levels
are available for time-critical process data and IRT for high-accuracy and also isochronous
processes .
Communications processor
Communication processors are modules used for point-to-point and bus connections.
Configuring
Selecting and putting together individual components of an automation system or installing
necessary software and adapting it for a specific application (for example, by configuring the
modules).
Consistent data
Data which belongs together in terms of content and must not be separated is known as
consistent data.
For example, the values of analog modules must always be handled as a whole, that is, the
value of an analog module must not be corrupted as a result of reading out at two different
points in time.
CP
→ Communications processor
CPU
C entral P rocessing U nit - Central module of the S7 automation system with a control and
arithmetic unit, memory, operating system and interface for programming device.