Allen-Bradley MicroLogix 1200 Reference Manual page 410

Glossary 4
Publication 1762-RM001C-EN-P
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
Input and Output
jump
Changes the normal sequence of program execution. In ladder programs
a JUMP (JMP) instruction causes execution to jump to a specific rung in
the user program.
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 (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.
low byte
Bits 0 to 7 of a word.
logic
A general term for digital circuits or programmed instructions to perform
required decision making and computational functions.
Master Control Relay (MCR)
A hard-wired relay that can be de-energized by any series-connected
emergency stop switch.
mnemonic
A simple and easy to remember term that is used to represent a complex
or lengthy set of information.
Modbus™ RTU Slave
A half-duplex serial communication protocol.