5
Installation notes
Industrial Ethernet networks
Manual – MOVIPRO
®
with EtherNet/IP™ or Modbus/TCP Fieldbus Interface
27
Network class
The first byte of the IP address determines the network class and as such represents
the division into network addresses and node addresses:
Range of values
(Byte 1 of IP ad-
dress)
Network
class
Example: Complete network
address
Meaning
0–127 A 10.1.22.3
10 = Network address
1.22.3 = Node address
128–191 B 172.16.52.4
172.16 = Network address
52.4 = Node address
192–223 C 192.168.10.4
192.168.10 = Network address
4 = Node address
Node addresses that consist only of zeros or ones are not permitted. The smallest ad-
dress (all bits are zero) describes the network itself and the largest address (all bits
are 1) is reserved for the broadcast.
This rough division is not sufficient for a number of networks. The networks also use
an explicit, adjustable subnet mask.
Subnetwork mask
A subnet mask is used to divide the network classes into even finer sections. Like the
IP address, the subnet mask is represented by 4 decimal numbers separated by
decimal points.
Each decimal number stands for 1 byte (8 bits) of the subnet mask and can also be
represented using binary code:
Exemplary subnet mask: 255.255.255.128
Byte Decimal Binary
1 255 11111111
2 255 11111111
3 255 11111111
4 128 10000000
The binary representation of the IP address and the subnet mask shows that in the
subnet mask, all bits of the network address are set to 1 and only the bits of the node
addresses have the value 0:
IP address: 192.168.10.129 Subnet mask: 255.255.255.128
Bytes 1–4 Bytes 1–4
Network address
11000000 11111111
10101000 11111111
00001010 11111111
Node address 10000001 10000000
The class C network with the network address 192.168.10 is further subdivided into
the following 2 networks by the subnet mask 255.255.255.128:
Network address Node addresses
192.168.10.0 192.168.10.1–192.168.10.126
192.168.10.128 92.168.10.129–192.168.10.254
The network nodes use a logical AND operation for the IP address and the subnet
mask to determine whether there is a communication partner in the same network or
in a different network. If the communication partner is in a different network, the stand-
ard gateway is addressed for passing on the data.
Standard gateway
The standard gateway is also addressed via a 32-bit address. The 32-bit address is
represented by 4 decimal numbers separated by decimal points.
16998413/EN – 12/2016
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