National Instruments 6023E, 6024E, 6025E Differential Connections for Nonreferenced or Floating Signal Sources

Chapter4 SignalConnections
©NationalInstruments Corporation 4-15 6023E/6024E/6025EUser Manual
Differential Connections for Nonreferenced or
Floating Signal Sources
Figure 4-6 shows how to connect a floating signal source to a channel
configured in DIFF input mode.
Figure4-6. DifferentialInput Connections for Nonreferenced Signals
Figure 4-6 showstwo bias resistors connected in parallel with the signal
leads of a floating signal source. If you do not use the resistors and the
source is truly floating, the source is not likely to remain within the
common-modesignal range of the PGIA. The PGIA then saturates, causing
erroneous readings.
+
–
+
Floating
Signal
Source
InputMultiplexers
VmMeasured
Voltage
–
–
+
I/OConnector
AIGND
Bias
Current
Return
Paths
Bias
resistors
(seetext)
ACH–
ACH+
AISENSE
SelectedChannel in DIFF Configuration
PGIA
ProgrammableGain
Instrumentation
Amplifier
Vs