Rockwell Automation 2100-ENET CENTERLINE 2100 Motor Control Centers EtherNet/IP Network Adapter - Manual (Page 65)

Rockwell Automation Publication 2100-UM006A-EN-P - July 2013 65
Glossary
I
I/O Data I/O data, sometimes called implicit messages or input/output, is time-critical
data such as a Logic Command and Reference. The terms input and output are
defined from the controller’s point of view. Output is produced by the controller
and consumed by the adapter. Input is produced by the adapter and consumed by
the controller.
IP Addresses 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...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 varies 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 be sure 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 powerup.
M
Master-Slave Hierarchy An adapter configured for a master-slave hierarchy exchanges data with the
master device. Usually, a network has one scanner that is the master device, and
all other devices (for example, E3 Plus overloads connected to EtherNet/IP
network adapters) are slave devices.
On a network with multiple scanners (called a multimaster hierarchy), each slave
device must have a scanner specified as a master.
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