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TCP/IP Ethernet Communications User’s Manual - August 1997 GFK-1084B
DCS Words See Detailed Channel Status Words.
Detailed Channel Status Words Two status words containing detailed information on
a single Series 90 channel. The DCS words are retrieved using the Retrieve Detailed
Channel Status Command.
Data Communications Equipment (DCE) Examples: Modems and transceivers.
Distinct from DTE, Data Terminal Equipment.
Data Link Layer In Open Systems Interconnection architecture, the layer (Layer 2) that
provides services to transfer data over a physical link between open systems.
Consists of the LLC and MAC sublayers.
Data Terminal Equipment Examples: computers, terminals, printers. Distinct from
DCE, Data Communications Equipment.
Dotted Decimal The notation for IP, gateway, and name server addresses as well as the
subnet mask. It consists of 4 decimal numbers (0-255) separated by periods.
Example IP address: 220.127.116.11
Ethernet Interface The general term used in this manual to identify the GEnet
hardware module, with or without software, that connects a PLC (or CNC) to a
network. It may also appear in the shortened form, “Interface”. (See also LAN
Flash Memory A type of read-only memory that can be erased and reprogrammed
under local software control. It is used to store data that must be preserved when
power is off..
Frame A data structure that consists of fields, predetermined by a protocol, for the
transmission of user data and control data.
Gateway A special purpose, dedicated computer that attaches to two or more networks
and routes packets from one to the other. In particular, an Internet gateway routes
IP datagrams among the networks to which it connects. Gateways route packets to
other gateways until they can be delivered to the final destination directly across the
physical network. (Also sometimes referred to as a router.)
Global Address Administration Address administration in which all LAN individual
addresses are unique within the same or other Local Area Networks. (See also, Local
Group Address An LLC address that identifies a group of network nodes on a Local
Host A computer or workstation that communicates with stations such as PLCs or
CNCs across a network, especially one that performs supervisory or control
functions. Note that this same term is widely used in TCP/IP literature to refer to
any network node that can be a source or destination for network messages. (See
Hostid The hostid is the part of the IP address identifying the host on the network.
(See also Netid.)
IEEE 802 The IEEE 802 LAN series of standards are as follows:
IEEE 802 Overview and Architecture.
IEEE 802.2 The Logical Link Control (LLC) sublayer of OSI Data Link Layer common
above all IEEE 802 Medium Access Control (MAC) sublayers.