Glossary
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National Instruments Corporation
G-7
NI PCI-7342 Hardware User Manual
N
noise
an undesirable electrical signal—noise comes from external sources such
as the AC power line, motors, generators, transformers, fluorescent lights,
soldering irons, CRT displays, computers, electrical storms, welders, radio
transmitters, and internal sources such as semiconductors, resistors, and
capacitors. Noise corrupts signals you are trying to send or receive.
noninverting
the polarity of a switch (limit switch, home switch, etc.) in
active
state. If
these switches are active-high, they are said to have non-inverting polarity.
O
open-loop
refers to a motion control system where no external sensors (feedback
devices) are used to provide position or velocity correction signals
open collector
refers to a transistor current that can only sink current, allowing multiple
devices to communicate bidirectionally on a single line
P
PCI
Peripheral Component Interconnect—a high-performance expansion bus
architecture originally developed by Intel to replace ISA and EISA. It is
achieving widespread acceptance as a standard for PCs and workstations;
it offers a theoretical maximum transfer rate of 132 MB/s.
PID
proportional-integral-derivative control loop
PIVff
proportional-integral-velocity feedforward
port
(1) a communications connection on a computer or a remote controller
(2) a digital port, consisting eight lines of digital input and/or output
position breakpoint
position breakpoint for an encoder can be set in absolute or relative
quadrature counts. When the encoder reaches a position breakpoint, the
associated breakpoint output immediately transitions.
power cycling
turning the host computer off and then back on, which causes a reset of
the motion control board
