Rockwell Automation 1732E-OB8M8SR EtherNet/IP Dual Port 8-Point SOE Input and Scheduled Output Modules UM - Manual (Page 35)

Rockwell Automation Publication 1732E-UM003B-EN-E - March 2014 25
Configure the Module for Your EtherNet/IP Network Chapter 5
IP addresses are written as four decimal integers (0...255) separated by periods
where each integer gives the value of one byte of the IP address.
Gateway Address
This section applies to multi-network systems. If you have a single network
system, go to the next section.
The gateway address is the default address of a network. It provides a single
domain name and point of entry to the site. Gateways connect individual
networks into a system of networks. When a node needs to communicate with a
node on another network, a gateway transfers the data between the two
networks. The following figure shows gateway G connecting Network 1 with
Network 2.
When host B with IP address 128.2.0.1 communicates with host C, it knows
from C’s IP address that C is on the same network. In an Ethernet environment,
B then resolves C’s IP address into a hardware address (MAC address) and
communicates with C directly.
When host B communicates with host A, it knows from A’s IP address that A is
on another network (the net IDs are different). In order to send data to A, B must
have the IP address of the gateway connecting the two networks. In this example,
the gateway’s IP address on Network 2 is 128.2.0.3.
The gateway has two IP addresses (128.1.0.2 and 128.2.0.3). The first must be
used by hosts on Network 1 and the second must be used by hosts on Network 2.
To be usable, a host’s gateway must be addressed using a net ID matching its own.
EXAMPLE For example, the 32-bit IP address:
10000000 00000001 00000000 00000001 is written as
128.1.0.1.
Network 1
Network 2
128.2.0.3
128.1.0.2
128.1.0.1
128.2.0.1 128.2.0.2
A
B C
G