Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 509)

Glossary
G–5
protocol: The packaging of information that is transmitted across a network.
read: To acquire data from a storage place. For example, the controller
READs information from the input data file to solve the program.
relay: An electrically operated device that mechanically switches electrical
circuits.
relay logic: A representation of the program or other logic in a form
normally used for relays.
restore: To download (transfer) a program from a personal computer to a
controller.
reserved bit: A status file location that the user should not read or write to.
retentive data: Information associated with data files (timers, counters,
inputs, and outputs) in a program that is preserved through power cycles.
Program files 2–15 are not effected by retentive data.
RRUN mode: remote mode during which the controller scans or executes
the logic program, monitors input devices, energizes output devices, and acts
on enabled I/O forces.
RS–232: An EIA standard that specifies electrical, mechanical, and
functional characteristics for serial binary communication circuits. A
single–ended serial communication interface.
run mode: When the program in the controller is being executed, inputs are
read, the program is scanned, and outputs are energized and de–energized.
rung: Ladder logic is comprised of a set of rungs. 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. If all paths are false, the outputs are made false.
scan time: The time required for the controller to execute the instructions in
the program. The scan time may vary depending on the instructions and each
instruction’s status during the scan.
sinking: A term used to describe current flow between an I/O device and
controller I/O circuit — typically, a sinking device or circuit provides a path
to ground, low, or negative side of power supply.
software: Executable programming package used to develop ladder
diagrams.
sourcing: A term used to describe current flow between an I/O device and
controller I/O circuit — typically, a sourcing device or circuit provides a path
to the source, high, or positive side of power supply.
status: The condition of a circuit or system, represented as logic 0 (OFF) or
1 (ON).