Siemens SIMATIC ET 200AL, System Manual

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Glossary
PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL
327
System redundancy AR
In a redundant system, an IO device with system redundancy S2 has a system redundancy AR
with each of the two CPUs (IO controllers).
System states
The system states of the redundant S7-1500R/H system result from the operating states of
the primary and backup CPUs. The concept of the system state is used to obtain a simplified
expression that characterizes the simultaneously occurring operating states of the two CPUs.
The following system states are available for the redundant S7-1500R/H system: STOP,
STARTUP, RUN-Solo, SYNCUP and RUN-Redundant.
TCP/IP
The Ethernet itself is only a transport system for data - similar to a highway, which is a
transport system for people and goods. The actual data transport is performed by so-called
protocols - similar to cars and trucks, which transport people and goods on the highway.
The two basic protocols TCP (
T ransmission C ontrol P rotocol) and IP ( I nternet P rotocol) -
TCP/IP for short - perform the following tasks:
1.
The data is broken down into packets at the sender.
2. The packets are transported over the Ethernet to the correct recipient.
3. At the recipient, the packets are reassembled in the correct order.
4. Corrupt packets continue to be sent until they are received correctly.
Most higher-level protocols use TCP/IP to perform their duties. H yper T ext T ransfer P rotocol
(HTTP), for example transfers documents written in H yper T ext M arkup L anguage (HTML) in
the W orld W ide W eb (WWW). This technique is what enables you to view web pages in your
Internet browser in the first place.
Topology configuration
All the interconnected ports of the PROFINET devices in the STEP 7 project and their
relationships to each other.
Twisted-pair
Fast Ethernet via twisted-pair cables is based on the IEEE 802.3u standard (100 Base-TX). The
transmission medium is a shielded 2x2 twisted-pair cable with an impedance of 100 Ω
(AWG 22). The transmission characteristics of this cable must meet the requirements of
category 5.
The maximum length of the connection between the terminal and the network component
must not exceed 100 m. The connectors are designed according to the 100Base-TX standard
with the RJ45 connector system.