Network Structures; Network Topologies; Linear Structure - Siemens SIMATIC NET System Manual

2.2

Network structures

2.2.1

Network topologies

Network topologies are oriented according to the requirements of the equipment to be
networked. The most common topologies include bus, star and ring structures. In practice,
plants usually consist of mixed structures. These can be implemented both with electrical
cables as well as with optical cables (fiber-optic cables).
Glass fiber-optic cables are used for long distances. For short distances, plastic fiber optic
cables, such as Polymer Optic Fiber (POF), or plastic cladded glass fibers, such as Polymer
Cladded Fiber (PCF), are available.
2.2.2

Linear structure

Linear bus
The linear bus is the simplest network structure. It is characterized by a backbone of the
network to which the individual nodes can be connected directly or through individual
branches, whereby each branch contains only one node.
● The advantage of the linear bus topology is its simple setup and low hardware
investment. It is suitable, for example, for the large-scale interconnection of rigidly
coupled machines, such as in a production line.
● The disadvantages of bus topologies are that the resources are not put to optimum use
and that there is no redundancy: A break on the cable at any point cannot be bridged.
Connecting the ends of the linear bus, on the other hand, creates a ring with which these
disadvantages can be avoided.
Figure 2-2
Industrial Ethernet
System Manual, 09/2019, C79000-G8976-C242-10
Linear network topology with Industrial Ethernet as an example
Network structures and network configuration
2.2 Network structures
75