Analog Input Modes; Taking Differential Measurements - National Instruments USB-6001 User Manual

Analog Input Modes

You can configure the analog input channels on the NI DAQ device to take up to four differential
(DIFF) or eight referenced single-ended (RSE) measurements.
• Differential mode—In DIFF mode, the NI DAQ device measures the difference in voltage
between two AI signals.
• Referenced single-ended mode—In RSE mode, the NI DAQ device measures the voltage
of an AI signal relative to AI GND.
Analog input modes are programmed on a per-channel basis. For example, you can configure
the device to scan two channels in differential mode and four channels on single-ended mode.
The AI settings determine how you connect your AI signals to the NI DAQ device.

Taking Differential Measurements

For differential signals, connect the positive lead of the voltage signal or source to the
AI+ terminal, and the negative lead to the AI- terminal.
Figure 7. Example of a Differential
10
5
0
–5
–10
12 | ni.com | NI USB-6001/6002/6003 User Guide
Figure 6. Connecting a Differential Voltage Signal
Voltage
Source
AI+
DAQ Device
AI–
± 10 V Measurement
AI 1
AI 5
Result