Ai fifo, Analog input modes, Connecting differential voltage signals – National Instruments NI USB-6009 User Manual
Page 18: Figure 8. connecting a differential voltage signal
NI USB-6008/6009 User Guide and Specifications
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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 Table 6 for more
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 8. Connecting a Differential Voltage Signal
The differential input mode can measure ±20 V signals in the ±20 V range.
However, the maximum voltage on any one pin is ±10 V with respect to
GND. For example, if AI 1 is +10 V and AI 5 is –10 V, then the
measurement returned from the device is +20 V.
AI+
NI USB-6008/6009
AI–
Voltage
Source