Allen-Bradley ControlLogix 1756-ENBT, User Manual

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Publication 1756-UM050A-EN-P - December 2001
Glossary 3
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.
Host Name
The Host Name is the unique name for a computer within its domain.
It’s always the first element of a full name, and, with its domain and
top-level domain suffix, creates the unique name of that computer on
the Internet. For example, let’s say the foobar website is
www.foobar.com. The Host Name is “www”, which is not unique on
the web, but is unique within the foobar domain.
The Host Name can also refer to the Fully Qualified Domain Name, or
in this example, www.foobar.com. Both naming methods seem to be
used interchangeably in various documents. For the purposes of this
document, the Host Name will refer to the FQDN, or as in this
example, www.foobar.com.
Hub
A central connecting device that joins devices together in a star
configuration. Hubs are generally not suitable for use in I/O control
systems, since they are time critical applications that cannot tolerate
lost packets.
Implicit Messaging
Real time messaging of I/O data.
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