National Instruments Network Device DAQ S - Manual (Page 156)

Glossary
© National Instruments Corporation G-3 NI 6124/6154 User Manual
channel 1. Physical—a terminal or pin at which you can measure or generate an
analog or digital signal. A single physical channel can include more than
one terminal, as in the case of a differential analog input channel or a digital
port of eight lines. The name used for a counter physical channel is an
exception because that physical channel name is not the name of the
terminal where the counter measures or generates the digital signal.
2. Virtual—a collection of property settings that can include a name, a
physical channel, input terminal connections, the type of measurement or
generation, and scaling information. You can define NI-DAQmx virtual
channels outside a task (global) or inside a task (local). Configuring virtual
channels is integral to every measurement you take in NI-DAQmx. In
NI-DAQmx, you can configure virtual channels either in MAX or in a
program, and you can configure channels as part of a task or separately.
chassis ground Any connection back to the protective conductor earth ground. See also
earth ground .
cm Centimeter.
CMOS Complementary metal-oxide semiconductor.
CMRR Common-mode rejection ratio—a measure of the capability of an
instrument to reject a signal that is common to both input leads.
CompactPCI A Eurocard configuration of the PCI bus for industrial applications.
correlated DIO A feature that allows you to clock digital I/O on the same clock as
analog I/O.
counter/timer A circuit that counts external pulses or clock pulses (timing).
coupling The manner in which a signal is connected from one circuit to another.
When applied to instrument products or DAQ cards, it refers to the input
signal coupling technique.
CTR Counter signal.