National Instruments NI 6120 - Manual (Page 49)

Chapter 4 Connecting Signals
© National Instruments Corporation 4-11 NI 6115/6120 User Manual
Connections for Nonreferenced or Floating Signal Sources
Figures 4-4 and 4-5 show how to connect a floating signal source to a
channel on the NI 6115 and NI 6120, respectively.
Figure 4-4. Differential Input Connections on the NI 6115 for Nonreferenced Signals
+
–
ACH0 Connections Shown
PGIA
1 M
* 100 pf
*
10 nf
Bias
Resistor
(see text)
AC Coupling
V
m
I/O Connector
Bias
Current
Return
Paths
Floating
Signal
Source
Instrumentation
Amplifier
Measured
Voltage
ACH0GND
ACH0–
ACH0+
+
–
*
10 k Ω 40 pf for ranges > ±10 V
V
s
+
–
Common-Mode
Choke