Siemens SIMATIC PROFINET Function Manual page 253

Sync domain
All PROFINET devices to be synchronized with IRT via PROFINET IO must belong to a sync
domain.
The sync domain consists of exactly one sync master and at least one sync slave. An
IO controller or switch generally handles the role of the sync master.
Non-synchronized PROFINET devices are not part of a sync domain.
System diagnostics
System diagnostics refers to the detection, evaluation, and signaling of errors that occur
within the automation system, for example, programming errors or module failures. System
errors can be indicated by LEDs or in STEP 7.
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 (Transmission Control Protocol) and IP (Internet Protocol) -
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. Hyper Text Transfer Protocol
(HTTP), for example transfers documents written in Hyper Text Markup Language (HTML) in
the World Wide Web (WWW). This technique is what enables you to view web pages in your
Internet browser in the first place.
Topology
Structure of a network. Common structures include:
● Linear bus topology
● Ring topology
● Star topology
● Tree topology
Topology configuration
All the interconnected ports of the PROFINET devices in the STEP 7 project and their
relationships to each other.
PROFINET with STEP 7 V14
Function Manual, 09/2016, A5E03444486-AG
Glossary
253