User Documentation

Planning
2053260000/05/2015
11
2.1.2 Devices for external connection
Designate the end devices and their access points (I/O modules etc.).
1 Designate the number and spatial arrangement of the I/O modules.
2 Dene the terminals: exactly which terminals are required? In which protection
degree: IP 20, 54, 67…?
3 Data volume of the terminals: dene this at this point for the later
determination of the network equipment.
4 Dene the connections to external networks.
5 Dene the connections to the Internet.
6 Dene the remote maintenance access (e.g., via modem).
2.1.3 Network structure
Here, you should dene the complete structure which will be used to co-ordinate
the components later on.
Main networks and subnetworks
If necessary, subnetworks can be operated at a lower speed depending on the
volume of data. For example, the backbone (main line) can be operated with
Gigabit Ethernet and the subnetworks with Fast Ethernet.
Collision domains (CSMA and CD)
A collision domain is an interface in a network at which there is the possibility of
collisions. When, for example, several PCs are connected in series, collisions can
occur if two PCs attempt to transfer data in parallel to each other. Such collisions
can be avoided by using a router or switch which provides a separate port for
each PC. In the case of real-time applications, special attention must be paid to
avoiding collisions and thus time delays.