Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual - Manual (Page 277)

Publication 1747-UM011G-EN-P - June 2008
Glossary 277
instruction
A mnemonic defining an operation to be performed by the processor.
A rung in a program consists of a set of input and output instructions.
The input instructions are evaluated by the controller as being true or
false. In turn, the controller sets the output instructions to true or false.
instruction set
The set of instructions available within a controller.
I/O
Inputs and Outputs
IP address
A 32-bit address assigned to hosts that want to participate in a TCP/IP
internet. IP addresses are the abstraction of physical hardware
addresses, with a network and host partition which makes routing
efficient.
isolated link coupler
The link coupler provides an electrically isolated network connection
for an SLC 500 controller (processor or programming station). The link
couplers connect the daisy-chained DH-485 communication cable.
ladder logic
A graphical programming format resembling a ladder-like diagram.
The ladder logic programing language is the most common
programmable controller language.
least significant bit (LSB)
The element (or bit) in a binary word that carries the smallest value of
weight.
LED indicator
Light emitting diode. Used as status indicator for processor functions
and inputs and outputs.
LIFO (last-in-first-out)
The order that data is stored and retrieved from a file.