Rockwell Automation 22-COMM-E EtherNet/IP Adapter - Manual (Page 155)

Glossary G-5
I
I/O Data
I/O data, sometimes called “implicit messages” or “input/output,”
transmit time-critical data such as a Logic Command and Reference. The
terms “input” and “output” are defined from the scanner’s point of view.
Output is transmitted by the scanner and consumed by the adapter. Input
is transmitted by the adapter and consumed by the scanner.
IP Address
A unique IP address identifies each node on an EtherNet/IP network. An
IP address consists of 32 bits that are divided into four segments of one
byte each. It appears as four decimal integers separated by periods
(xxx.xxx.xxx.xxx). Each “xxx” can have a decimal value from 0 to 255.
For example, an IP address could be 192.168.0.1.
An IP address has two parts: a network ID and a host ID. The class of
network determines the format of the address.
The number of devices on your EtherNet/IP network will vary depending
on the number of bytes that are used for the network address. In many
cases you are given a network with a Class C address, in which the first
three bytes contain the network address (subnet mask = 255.255.255.0).
This leaves 8 bits or 256 addresses on your network. Because two
addresses are reserved for special uses (0 is an address for the network
usually used by the router, and 255 is an address for broadcast messages
to all network devices), you have 254 addresses to use on a Class C
address block.
To ensure that each device on the Internet has a unique address, contact
your network administrator or Internet Service Provider for unique fixed
IP addresses. You can then set the unique IP address for the adapter by
using a BOOTP server or by manually configuring parameters in the
adapter. The adapter reads the values of these parameters only at
power-up.
0 1 7 15 23 31
Class A 0 Network ID Host ID
0 1 7 15 23 31
Class B 1 0 Network ID Host ID
0 1 2 7 15 23 31
Class C 1 1 0 Network ID Host ID