Allen-Bradley MicroLogix 1200 User Manual page 149

Glossary 5
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 entered into and retrieved from a file.
low byte
Bits 0 to 7 of a word.
logic
A process of solving complex problems through the repeated use of
simple functions that can be either true or false. General term for
digital circuits and programmed instructions to perform required
decision making and computational functions.
Master Control Relay (MCR)
A mandatory hard-wired relay that can be de-energized by any
series-connected emergency stop switch. Whenever the MCR is
de-energized, its contacts open to de-energize all application I/O
devices.
mnemonic
A simple and easy to remember term that is used to represent a
complex or lengthy set of information.
modem
Modulator/demodulator. Equipment that connects data terminal
equipment to a communication line.
modes
Selected methods of operation. Example: run, test, or program.
negative logic
The use of binary logic in such a way that "0" represents the voltage
level normally associated with logic 1 (for example, 0 = +5V, 1 = 0V).
Positive is more conventional (for example, 1 = +5V, 0 = 0V).
Publication 1762-UM001D-EN-P - March 2004