GE GFK-1541B manual Bootp, Extended Netid See Subnet Id

A

CSMA/CD See Carrier Sense Multiple Access with Collision Detection.

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.

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.

Directory Information Base (DIB) A collection of information used for directory services (like name resolution). In this document DIB refers to the DDP database which is actually distributed among all DDP devices instead of in a single name server. (See also Distributed Directory Protocol (DDP)).

Distributed Directory Protocol (DDP) The GE Fanuc proprietary protocol used to provide distributed name service on a TCP/IP Ethernet network. The distributed nature of DDP means that there is no centralized name server.

Domain Name System (DNS) The predominant name service protocol used by the Internet. DNS is primarily used to resolve a name into an IP address.

Dotted-DecimalThe 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: 10.0.0.1

Duplex The ability to send and receive data simultaneously (full duplex) or not (half duplex).

Dynamic Host Configuration Protocol (DHCP) A superset of the BOOTP protocol (See

BOOTP.)

Ethernet Global Data (EGD) A proprietary protocol that provides efficient connectionless periodic data transfer over an Ethernet network. Operates over the UDP protocol.

Ethernet Interface The general term used in this manual to identify the GE Fanuc 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 Interface.)

Exchange In Ethernet Global Data, a set of variables or memory locations within the PLC or other device to be transferred from a Producer to a Consumer. (See also Producer, Consumer.)

Exchange ID In Ethernet Global Data, a numerical value assigned by the user to identify a specific data exchange to be sent by the producing device. (See also Producer, Consumer, Exchange.)

Exchange Status Word The 16-bit Exchange Status word continuously indicates the status of an Ethernet Global Data exchange.

Extended Netid See Subnet Id.

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.

GFK-1541B Appendix A Glossary A-3