Rockwell Automation T8094 8000 Series TMR System Safety Manual - Manual (Page 10)

SAFETY MANUAL
D oc N umber T8094
I ssue 27 – June 2013
Page x
GLOSSARY
Actuators Devices which cause an action (electrical,
mechanical, pneumatic, etc.) to occur when
required within a plant component.
Architecture Organisational structure of a computing system
which describes the functional relationship
between board level, device level and system
level components.
ASCII The American Standard Code for Information
Interchange
. Uses seven bits to represent 128
characters. Both upper and lower case letters,
numbers, special symbols and a wide range of
control codes are included.
Availability The probability that a system will be able to
perform its designated function when required
for use – normally expressed as a percentage.
Asynchronous A data communications term describing the
method by which signals between computers
are timed. Although the number of characters
to be sent per second is undefined, the rate at
which a character’s bits are sent is pre-
determined. Each character is preceded by a
start bit and terminated by a stop bit.
Backplane A printed circuit board which supports bussed
functions to connectors mounted on a printed
circuit board. Plug-in components and modules
are then able to connect to the bus pins.
Buffer A type of memory in which information is stored
temporarily during transfer from one device to
another, or one process to another. Normally
used to accommodate the difference in the rate
or time at which the devices can handle the
data.
Bus A group of conductors which carry related data.
Micro-based systems have an Address Bus,
Data Bus and a Control Bus.
CIE Control Indicating Equipment
Companion Slot Spare (standby) slot position adjacent (to the
right) to the slot occupied by the ‘active’
module. The slots are inter-connected to enable
the ‘active’ module to be ‘hot’ replaced as
necessary.
Controller A Controller is the heart of any Rockwell
Automation microprocessor based system. It
performs central processing of user application
logic and controls the actions of input and
output hardware, as well as peripheral hardware
such as printers and Visual Display Units.