Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual - Manual (Page 273)

Publication 1747-UM011G-EN-P - June 2008
Glossary 273
controller
A device, such as a programmable controller, used to control output
devices.
controller overhead
A portion of the operating cycle used for housekeeping purposes (for
example, memory checks, tests, and communication).
control profile
The means by which a controller determines which outputs turn on
under what conditions.
counter
A device that counts the occurrence of some event.
CPU (central processing unit)
The decision-making and data storage section of a programmable
controller.
data table
The part of processor memory that contains I/O status and files where
user data (such as bit, integer, timers, and counters) is monitored,
manipulated, and changed for control purposes.
DHCP (Dynamic Host Configuration Protocol)
A protocol used to assign dynamic IP addresses to devices residing on
a network.
DF1 protocol
A peer-to-peer link-layer protocol that combines features of ANSI
X3.28-1976 specification subcategories D1 (data transparency) and F1
(two-way simultaneous transmission with embedded responses).
DIN rail
Manufactured according to Deutsche Industrie Normenausshus (DIN)
standards, a metal railing designed to ease installation and mounting
of your devices.