Glossary – Rockwell Automation 1756-OF8H ControlLogix HART Analog I/O Modules User Manual
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Rockwell Automation Publication 1756-UM533C-EN-P - February 2011
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Glossary
The following terms and abbreviations are used throughout this manual.
For definitions of terms not listed here, refer to the Allen-Bradley Industrial
Automation Glossary, publicat
balanced circuit
1) A circuit whose two sides are electrically alike and symmetrical to a common
reference point, usually ground. 2) Contrasted with unbalanced circuit
).
broadcast
Data transmissions to all addresses.
CIP
Acronym for Common Industrial Protocol; a communication protocol, or
language, between industrial devices. CIP provides seamless communication for
devices on DeviceNet, ControlNet, and EtherNet/IP networks.
compatible match
An Electronic Keying Protection mode that requires the physical module and the
module configured in the software to match according to vendor, catalog
number, and major revision. The minor revision of the module must be greater
than or equal to that configured.
connection
The continuous communication mechanism from the controller to an I/O
module in the control system.
ControlBus
The backplane used by the 1756 chassis.
coordinated system time (CST)
Timer value, which is kept synchronized for all modules within a single
ControlBus chassis. The CST is a 64-bit number with microsecond resolution.
differential
1) Pertaining to a method of signal transmission through two wires. The
transmission always has opposite states. The signal data is the polarity difference
between the wires; when one is high, the other is low. Neither wire is grounded.
The circuit may be either a balanced circuit, a floating circuit, or a circuit with a
high-impedance path to ground from either end. Usually used in reference to
encoders, analog I/O circuits, and communication circuits. 2) Contrasted with
single-ended
(
direct connection
An I/O connection, where the controller establishes an individual connection
with I/O modules.
disable keying
An option that turns off all electronic keying to the module. Requires no
attributes of the physical module and the module configured in the software to
match. A connection is attempted to the module even if it is the wrong type.
download
The process of transferring the contents of a project on the workstation into the
controller.
electronic keying
A system feature that makes sure that physical module attributes are consistent
with what was configured in software.