Glossary
G-8
ni.com
start trigger
A TTL level signal having two discrete levels, a high and a low level, that
starts an operation.
synchrono
u
s
A property of an event that is synchronized to a reference clock.
T
TC
terminal co
u
nt—a strobe that occ
u
rs when a co
u
nter reaches zero from
either direction.
termination
Matching of impedances at the end of a signal path to minimize reflections.
timebase
Another term
u
sed for the SOURCE of a co
u
nter. Us
u
ally indicates an
internal SOURCE provided by or derived from an onboard oscillator.
trigger
Any event that ca
u
ses, starts, or stops some form of data capt
u
re.
tri-state
A third o
u
tp
u
t state, other than high or low, in which the o
u
tp
u
t is
u
ndriven.
TTL
transistor-transistor logic
two-p
u
lse encoder
A motion encoder that has two channels: channels A and B. P
u
lses on
channel A indicate movement in one direction while p
u
lses on channel B
indicate movement in the opposite direction. This type of encoder is also
referred to as
u
p down encoder.
U
u
nstrobed digital I/O
A type of digital inp
u
t or o
u
tp
u
t in which software reads or writes the
digital line or port states directly, witho
u
t
u
sing any handshaking or
hardware-controlled timing f
u
nctions. Also called immediate,
nonhandshaking, or
u
nlatched digital I/O.
UP_DOWN
The signal that determines whether a co
u
nter increments or decrements.
V
V
volts
VDC
volts direct c
u
rrent