Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual - Manual (Page 282)

Publication 1747-UM011G-EN-P - June 2008
282 Glossary
programming device
Programming package used to develop ladder logic diagrams.
protocol
The language or packaging of information that is transmitted across a
network.
(I/O) rack
An I/O addressing unit that corresponds to 8 input image-table words
and 8 output image-table words. A rack can contain a maximum of 8
I/O groups for up to 128 discrete I/O.
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.
remote I/O network
A network where the communication between the processor and the
I/O is across a serial link.
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.