Glossary
©
National Instruments Corporation
G-9
I
I/O
Inp
u
t/O
u
tp
u
t—The transfer of data to/from a comp
u
ter system involving
comm
u
nications channels, operator interface devices, and/or data
acq
u
isition and control interfaces.
impedance
1. The electrical characteristic of a circ
u
it expressed in ohms and/or
capacitance/ind
u
ctance.
2. Resistance.
in.
Inch or inches.
instr
u
ment driver
A set of high-level software f
u
nctions that controls a specific GPIB, VXI,
or RS232 programmable instr
u
ment or a specific pl
u
g-in DAQ device.
Instr
u
ment drivers are available in several forms, ranging from a f
u
nction
callable lang
u
age to a virt
u
al instr
u
ment (VI) in LabVIEW.
instr
u
mentation
amplifier
A circ
u
it whose o
u
tp
u
t voltage with respect to gro
u
nd is proportional to the
difference between the voltages at its two inp
u
ts. An instr
u
mentation
amplifier normally has high-impedance differential inp
u
ts and high
common-mode rejection.
interchannel delay
Amo
u
nt of time that passes between sampling consec
u
tive channels in an
AI scan list. The interchannel delay m
u
st be short eno
u
gh to allow sampling
of all the channels in the channel list, within the sample interval. The
greater the interchannel delay, the more time the PGIA is allowed to settle
before the next channel is sampled. The interchannel delay is reg
u
lated by
AI Convert Clock.
interface
Connection between one or more of the following: hardware, software, and
the
u
ser. For example, hardware interfaces connect two other pieces of
hardware.
interr
u
pt, interr
u
pt
req
u
est line
1. A means for a device to notify another device that an event occ
u
rred.
2. A comp
u
ter signal indicating that the CPU sho
u
ld s
u
spend its c
u
rrent
task to service a designated activity.
I
OH
C
u
rrent, o
u
tp
u
t high.
I
OL
C
u
rrent, o
u
tp
u
t low.
IRQ
See
interr
u
pt, interr
u
pt req
u
est line.
