Glossary
©
National Instruments Corporation
G-7
ppb
parts per billion
prescaling
The division of freq
u
ency of an inp
u
t signal that is to be
u
sed as SOURCE
of a co
u
nter.
programmed I/O
A data transfer method in which the CPU reads or writes data as prompted
by software.
PXI
Mod
u
lar instr
u
mentation standard based on CompactPCI developed by
National Instr
u
ments with enhancements for instr
u
mentation.
R
reflection
A high-speed signal transition behaves like a wave and is reflected like a
wave at an inadeq
u
ately terminated endpoint. This phenomenon is referred
to as reflection.
RG
reserved gro
u
nd. Pins that are marked RG on the I/O connector are
no-connects if yo
u
u
se the SH100-100-S2 shielded cable, while they are
gro
u
nd pins if yo
u
u
se the R100100
u
nshielded ribbon cable.
ribbon cable
A flat cable in which the cond
u
ctors are side by side.
ringing
The oscillation of a signal abo
u
t a high-voltage or low-voltage state
immediately following a transition to that state.
RTSI B
u
s
real-time system integration b
u
s—the National Instr
u
ments timing b
u
s that
connects DAQ boards directly, by means of connectors on top of the boards,
for precise synchronization of f
u
nctions.
S
s
seconds
(HW) Save register
A register inside the NI-TIO ASIC that stores the res
u
lt of a meas
u
rement.
so
u
rce
In the co
u
nter context, so
u
rce refers to the signal that ca
u
ses the co
u
nter to
increment or decrement. In the context of signals, so
u
rce refers to the
device that drives a signal.
SOURCE
The signal that ca
u
ses the co
u
nter to increment or decrement.
