National Instruments 6008

PGA

The progammable-gain amplifier provides input gains of 1, 2, 4, 5, 8,

10, 16, or 20 when configured for differential measurements and gain

of1 wh en configured for single-ended measurements. The PGA gain is

automatically calculated based on the voltage range selected in the

measurement application.

A/D Converter

The analog-to-digital converter (ADC) digitizes the AI signal by

converting the analog voltage into a digital code.

AI FIFO

The NI USB-6008/6009 can perform both single and multiple A/D

conversions of a fixed or infinite number of samples. A first-in-first-out

(FIFO) buffer holds data during AI acquisitions to ensure that no data

is lost.

Analog Input Modes

You can configure the AI channels on the NI USB-6008/6009 to take

single-ended or differential measurements. Refer to Table5 for mo re

information about I/O connections for single-ended or differential

measurements.

Connecting Differential Voltage Signals

For differential signals, connect the positive lead of the signal to the AI+

terminal, and the negative lead to the AI– terminal.

Figure 7. Connecting a Differential Voltage Signal

AI+

Voltage

Source NI USB-6008/6009

AI–