National Instruments NI USB-6009 User Manual

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© National Instruments Corporation
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NI USB-6008/6009 User Guide and Specifications
Figure 9.  Example of a Differential 20 V Measurement
Connecting a signal greater than ±10 V on either pin results in a clipped 
output.
Figure 10.  Exceeding ±10 V on AI Returns Clipped Output
Connecting Reference Single-Ended Voltage Signals
To connect reference single-ended voltage signals (RSE) to the 
NI USB-6008/6009, connect the positive voltage signal to the desired 
AI terminal, and the ground signal to a GND terminal, as illustrated in 
Figure 11.
When no signals are connected to the analog input terminal, the internal 
resistor divider may cause the terminal to float to approximately 1.4 V 
when the analog input terminal is configured as RSE. This behavior is 
normal and does not affect the measurement when a signal is connected.
–5
–10
–15
–20
20
15
10
5
0
Amplitude (V)
AI 1
AI 5
Result
–5
–10
–15
–20
20
15
10
5
0
Amplitude (V)
AI 1
AI 5
Result