Glossary
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ni.com
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.
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.
port
(1) A communications connection on a computer or a remote
controller. (2) A digital port, consisting of 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.
PWM
pulse width modulation—a method of controlling the average current
in a motor phase winding by varying the on-time (duty cycle) of
transistor switches.
PXI
PCI eXtensions for Instrumentation
