User Manual Owner's manual

Rockwell Automation Publication 280E-UM001B-EN-P - July 2012 57
Chapter 3
Introduction to EtherNet/IP and
Device Level Ring Technology
Terminology
Refer to the table for the meaning of common terms.
This Term Means
Consumer A destination device in the CIP™ networking model. See CIP.
CSMA/CD Carrier sense multiple access/collision detection is the access method used in
Ethernet. When a device wants to gain access to the network, it checks to see if
the network is quiet (senses the carrier). If it is not, it waits a random amount of
time before retrying. If the network is quiet and two devices access the line at
exactly the same time, their signals collide. When the collision is detected, they
both back off and each waits a random amount of time before retrying.
Determinism The ability to predict when information will be delivered. Important in time-
critical applications.
DHCP The dynamic host configuration protocol is an Internet protocol, similar to BootP,
for automating the configuration of computers that use TCP/IP. DHCP can be
used to automatically assign IP addresses, to deliver IP stack configuration
parameters, such as the subnet mask and default router, and to provide other
configuration information, such as the addresses for printer, time, and news
servers.
DNS The domain name system is a hierarchical, distributed method of organizing the
name space of the Internet. The DNS administratively groups hosts into a
hierarchy of authority that allows addressing and other information to be
widely distributed and maintained. A big advantage to the DNS is that using it
eliminates dependence on a centrally-maintained file that maps host names to
addresses.
Ethernet A physical layer standard using carrier sense multiple access with collision
detection (CSMA/CD) methods.
EtherNet/IP Ethernet industrial protocol applies a common industrial protocol (CIP) over
Ethernet by encapsulating messages in TCP/UDP/IP.
Ethernet network A local area network designed for the high-speed exchange of information
between computers and related devices.
Explicit messaging Non-time critical messaging used for device configuration and data collection,
such as downloading programs or peer-to-peer messaging between two PLC
units.
Full duplex A mode of communication that allows a device to send and receive information
at the same time, effectively doubling the bandwidth.