Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual - Manual (Page 283)

Publication 1747-UM011G-EN-P - June 2008
Glossary 283
RTB
Removable Terminal Block.
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).
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.
signal delay
For inputs, the response time required to transmit the circuit status
from the field wiring to the digital logic. For outputs, the time required
to transmit the circuit status from digital logic to the output wiring.
sinking
A term used to describe current flow between two devices. A sinking
device provides a direct path to ground.
sinking/sourcing
Describes a current signal flow relationship between field input and
output devices in a control system and their power supply. Sourcing
I/O modules supply (or source) current to sinking field devices.
Sinking I/O modules receive (or sink) current from sourcing field
devices.