FANUC Robotics America GFK-1541B User Manual
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Protocol A set of rules for exchanging messages between two communicating processes.
Protocol Data Unit (PDU) Information that is delivered as a unit between peer entities of a
Local Area Network (LAN) and that contains control information, address information, and
may contain data.
Remote Station A station located elsewhere on the network. (See also Local Station.)
Repeater In a Local Area Network (LAN), a device that amplifies and regenerates signals to
extend the range of transmission between network nodes or to interconnect two or more
segments. A repeater connects network nodes at the Physical Layer, ISO layer 1.
Responding Station A station which generates a message in response to a command that was
directed to the station.
Round-Trip Propagation Time Twice the time required for a bit to travel between the two
most distant nodes in a bus network.
NOTE: In a network using carrier sense, each frame must be long enough so that a collision
or jam signal may be detected by the transmitting node while this frame is being transmitted.
Its minimum length is therefore determined by the round-trip propagation time.
Router A device similar to a bridge that allows access to multiple LANs. Also known as a
gateway in Internet terminology. A router connects network nodes at the Network Layer,
ISO layer 3. (See also Gateway.)
Server A network node that provides specific services to other network nodes (clients). (See
also Client.)
EXAMPLE: File server, print server, name server, time server.
Service Request Transfer Protocol (SRTP) A proprietary protocol that encodes Series 90
“Service Requests”, the native language of the Series 90 PLC CPUs, to provide general
purpose communications with a Series 90 PLC. SRTP is presently available over
802.3/Ethernet networks. SRTP is also used by the PLC programming software to
communicate over an Ethernet network.
Signal Quality Error (SQE) An indication from the MAU (transceiver) to the Ethernet
Interface to indicate any of three conditions: 1) improper signals received from the medium,
2) collision detected, or 3) SQE message test.
Simple Network Time Protocol (SNTP) The Internet standard protocol used to synchronize the
real-time clocks of hosts over the network. (See also Time Synchronization.)
Slot Time ( in a CSMA/CD network) Minimum bitrate-dependent unit of time which, in case of
collision, is used to determine the delay after which network nodes may attempt to retransmit.
[Slot time for all IEEE 802.3 10 Mbps implementations is 51.2 µsec (512 bit times)].
Soft Switches Basic system information set up by the PLC programming software and
transferred to the LAN Interface upon powerup or restart.
Station A computer, PLC, or other device that connects to one or more networks. (See also
Node.)
Station Address Each node on an Ethernet network must have a unique MAC address which is
different from all other nodes on the network. This is a 12–digit hexadecimal MAC address.
(See also MAC Address.)
Station Manager A part of the basic Ethernet Interface communications software that executes
as a background activity on the Ethernet Interface. The Station Manager provides interactive
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