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Connector Information

The I/O Connector Signal Descriptions and +5 V Power sections contain information about NI 621x connectors. Refer to Appendix A, Device-Specific Information, for device I/O connector pinouts.

I/O Connector Signal Descriptions

Table 3-1describes the signals found on the I/O connectors. Not all signals are available on all devices.

Table 3-1.I/O Connector Signals

Signal Name

Reference

Direction

Description

 

 

 

 

 

 

 

 

AI GND

—

—

Analog Input Ground—These terminals are the

 

 

 

reference point for single-ended AI measurements in

 

 

 

RSE mode and the bias current return point for DIFF

 

 

 

measurements. All three ground references—AI GND,

 

 

 

AO GND, and D GND—are connected on the device.

 

 

 

 

AI <0..31>

Varies

Input

Analog Input Channels 0 to 31—Forsingle-ended

 

 

 

measurements, each signal is an analog input voltage

 

 

 

channel. In RSE mode, AI GND is the reference for these

 

 

 

signals. In NRSE mode, the reference for each

 

 

 

AI <0..31> signal is AI SENSE.

 

 

 

For differential measurements, AI 0 and AI 8 are the

 

 

 

positive and negative inputs of differential analog input

 

 

 

channel 0. Similarly, the following signal pairs also form

 

 

 

differential input channels:

 

 

 

<AI 1, AI 9>, <AI 2, AI 10>, <AI 3, AI 11>,

 

 

 

<AI 4, AI 12>, <AI 5, AI 13>, <AI 6, AI 14>,

 

 

 

<AI 7, AI 15>, <AI 16, AI 24>, <AI 17, AI 25>,

 

 

 

<AI 18, AI 26>, <AI 19, AI 27>, <AI 20, AI 28>,

 

 

 

<AI 21, AI 29>, <AI 22, AI 30>, <AI 23, AI 31>

 

 

 

 

AI SENSE

—

Input

Analog Input Sense—In NRSE mode, the reference for

 

 

 

each AI <0..31> signal is AI SENSE.

 

 

 

 

AO <0..1>

AO GND

Output

Analog Output Channels 0 to 1—These terminals

 

 

 

supply the voltage output of AO channels 0 to 1.

 

 

 

 

© National Instruments Corporation

3-1

NI USB-621x User Manual