Allen-Bradley MicroLogix 1200 Reference Manual page 413

Glossary 7
read
To acquire data. For example, the processor reads information from other
devices via a read message.
relay
An electrically operated device that mechanically switches electrical
circuits.
relay logic
A representation of binary or discrete logic.
restore
To transfer a program from a device to a controller.
reserved bit
A location reserved for internal use.
retentive data
Information (data) that is preserved through power cycles.
RS-232
An EIA standard that specifies electrical, mechanical, and functional
characteristics for serial binary communication circuits.
run mode
An executing mode during which the controller scans or executes the
logic program.
rung
A rung contains input and output instructions. During Run mode, the
inputs on a rung are evaluated to be true or false. If a path of true logic
exists, the outputs are made true (energized). If all paths are false, the
outputs are made false (de-energized).
RTU
Remote Terminal Unit
save
To save a program to a computer hard disk.
scan
The scan is made up of four elements: input scan, program scan, output
scan, and housekeeping.
scan time
The time required for the controller to complete one scan.
sinking
A term used to describe current flow between two devices. A sinking
device provides a direct path to ground.
Publication 1762-RM001C-EN-P