Rockwell Automation 1756-HSC ControlLogix High Speed Counter Module User Manual
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Publication 1756-UM007C-EN-P - November 2011
Glossary
117
data 1) A general term for any type of information. 2) In a more restricted sense,
data refers to the end-use information in the particular context; thereby
excluding the protocol information used to get the end-use information.
data table The part of processor memory that contains I/O values and files where data is
monitored, manipulated, and changed for control purposes.
database The entire body of data that has to do with one or more related subjects.
Typically, it consists of a collection of data files.
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 (
).
digital circuit 1) A switching circuit that has only two states: on and off. 2) A circuit that
provides a step function. 3) Contrasted with analog circuit (
).
direct connection An I/O connection where the controller establishes an individual connection
with I/O modules.
direct I/O module 1) An I/O module for which each input or output that has an individual
connection that corresponds directly to a data table bit or word that stores the
value of the signal at that I/O circuit (digital or analog). This allows the ladder
logic to have direct access to the I/O values. 2) Contrasted with intelligent
I/O module (
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).
disable keying 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.
download The process of transferring the contents of a project on the workstation into
the controller.
duration 1) The time during which something exists or lasts. For example, the length of
time that a signal is high may be described as the duration of a pulse. 2)
Compare interval (
) and period (
).
electronic keying A system feature which makes sure that the physical module attributes are
consistent with what was configured in the software.
encoder Any feedback element that converts linear or rotary position (absolute or
incremental) into a digital signal.
• Linear encoder—is a feedback element that directly converts linear
position (absolute or incremental) into a digital signal.