National Instruments NI 6239 用户手册

impedance

1. The electrical characteristic of a circuit expressed in ohms and/or 

capacitance/inductance.

2. Resistance.

in.

Inch or inches.

instrument driver

A set of high-level software functions that controls a specific GPIB, VXI, 
or RS232 programmable instrument or a specific plug-in DAQ device. 
Instrument drivers are available in several forms, ranging from a function 
callable language to a virtual instrument (VI) in LabVIEW.

instrumentation 
amplifier

A circuit whose output voltage with respect to ground is proportional to the 
difference between the voltages at its two inputs. An instrumentation 
amplifier normally has high-impedance differential inputs and high 
common-mode rejection.

interchannel delay

Amount of time that passes between sampling consecutive channels in an 
AI scan list. The interchannel delay must be short enough 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 regulated by 
ai/ConvertClock.

interface

Connection between one or more of the following: hardware, software, and 
the user. For example, hardware interfaces connect two other pieces of 
hardware.

interrupt, interrupt 
request line

1. A means for a device to notify another device that an event occurred.

2. A computer signal indicating that the CPU should suspend its current 

task to service a designated activity.

I

OH

Current, output high.

I

OL

Current, output low.

IRQ

See interrupt, interrupt request line.

isolation

An electrical break between any two signals or planes up to a given voltage.

isolation barrier

An electrical break between two electrical planes providing a given or set 
amount of electrical isolation. Current does not flow or transfer between the 
two sides of the isolation barrier.