Rockwell Automation 1756-NEX Nexus Module - Manual (Page 93)

Publication 1756-UM524B-EN-P - December 2008
Glossary
Application Program (AP) An upper layer program used for application pro-
cessing, including user processes and applications. An example of an applica-
tion program is a Logix5550 program.
Autonomous Decentralized Protocol (ADP) An Application Layer message
transfer protocol used in the NeXUS network.
BootP (Bootstrap Protocol) A low-level protocol that provides configurations
to other nodes on a TCP/IP network. BootP configuration files let you automati-
cally assign IP addresses to modules or other networked devices.
ControlBus The backplane used by the 1756 chassis. Acts as a network.
Control and Information Protocol (CIP) A communication protocol used to
transfer messages over ControlBus and ControlNet networks.
DHCP The Dynamic Host Configuration protocol (DHCP) is an Internet proto-
col, similar to BootP, for automatically configuring computers that use the
TCP/IP protocol. DHCP can be used to automatically assign IP addresses and
deliver TCP/IP stack configuration parameters (such as the subnet mask and
default router).
Ethernet A physical layer standard using Carrier sense Multiple Access with
Collision Detection (CSMA/CD) methods.
Message A basic data unit passed to the ADP by an Application Program or
delivered by the ADP to an Application Program.
NeXUS A trade name of a plant-floor TCP/IP over Ethernet type local area net-
work with the ADP protocol on the top.
NeXUS Node or Station Any PLC, computer or other physical device con-
nected to a NeXUS network.
Protocol Data Unit (PDU) PDU refers to a data unit passed to ADP from the
lower layer protocol (UDP or TCP) and vise versa. It consists of a header and a
message.
System Transaction A transaction generated when ADP detects an event (e.g.
fault status or internal status change) and is used as a notice to an application
program. The only system transaction currently defined in [1] is the Alive Sig-
nal (TCD=60003).