National Instruments NI 6221, User Manual

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Glossary
M Series User Manual G-14 ni.com
period The period of a signal, most often measured from one zero crossing to the
next zero crossing of the same slope. The period of a signal is the reciprocal
of its frequency (in Hz). Period is designated by the symbol T.
periods The number of periods of a signal.
PFI Programmable Function Interface.
PGIA Programmable Gain Instrumentation Amplifier.
physical channel See channel .
Plug and Play devices A specification prepared by Microsoft, Intel, and other PC-related
companies that result in PCs with plug-in devices that can be fully
configured in software, without jumpers or switches on the devices.
posttriggering The technique used on a DAQ device to acquire a programmed number of
samples after trigger conditions are met.
power source An instrument that provides one or more sources of AC or DC power. Also
known as power supply.
ppm Parts per million.
pretriggering The technique used on a DAQ device to keep a continuous buffer filled with
data, so that when the trigger conditions are met, the sample includes the
data leading up to the trigger condition.
pulse A signal whose amplitude deviates from zero for a short period of time.
pulse width The time from the rising to the falling slope of a pulse (at 50% amplitude).
PXI A rugged, open system for modular instrumentation based on CompactPCI,
with special mechanical, electrical, and software features. The PXIbus
standard was originally developed by National Instruments in 1997, and is
now managed by the PXIbus Systems Alliance.
PXI Express PCI Express eXtensions for Instrumentation—The PXI implementation
of PCI Express, a scalable full-simplex serial bus standard that operates at
2.5 Gbps and offers both asynchronous and isochronous data transfers.