Rockwell Automation 1734-AENT POINT I/O EtherNet/IP Adapter Module - Manual (Page 8)

Publication 1734-UM011D-EN-P - May 2011
viii Preface
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.
The 1734-AENT factory default is DHCP enabled. When you apply
power, the module sends a message containing its hardware address
to any DHCP server on the network. The server(s) replies by sending a
message with an appropriate IP address for the adapter. The adapter
responds by acknowledging to a server that it will use the offered IP
address.
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 application layer (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.
Fully qualified
domain name
A fully qualified domain name (FQDN) is a domain name that includes
all higher level domains relevant to the entity named. If you think of
the DNS as a tree-structure with each node having its own label, a
fully qualified domain name for a specific node would be its label
followed by the labels of all the other nodes between it and the root
of the tree. For example, for a host, a FQDN would include the string
that identifies the particular host, plus all domains of which the host
is a part, up to and including the top-level domain (the root domain is
always null). For example, PARIS.NISC.SRI.COM is a fully qualified
domain name for the host at 192.33.33.109.
Gateway A module or set of modules that allows communications between
nodes on dissimilar networks.
Term Definition