National Instruments NI 6014 - Manual (Page 41)

Chapter 4 Connecting Signals
© National Instruments Corporation 4-15 NI 6013/6014 User Manual
Single-Ended Connections for Floating Signal
Sources
Figure 4-6 shows how to connect a floating signal source to a channel
configured for NRSE mode on the NI 6013/6014.
Figure 4-6. Single-Ended Input Connections for Nonreferenced or Floating Signals
Single-Ended Connections for Grounded Signal
Sources
To measure a grounded signal source with a single-ended configuration,
you must configure the NI 6013/6014 in NRSE input mode. The signal
is then connected to the positive input of the PGIA, and the signal local
ground reference is connected to the negative input of the PGIA.
The ground point of the signal should, therefore, be connected to the
AISENSE pin. Any potential difference between the device ground and
the signal ground appears as a common-mode signal at both the positive
and negative inputs of the PGIA, and this difference is rejected by the
amplifier. If AISENSE is connected to AIGND in this situation, the
difference in ground potentials appears as an error in the measured voltage.
Selected Channel in NRSE Configuration
PGIA
Input Multiplexers
–
+
–
Floating
Signal
Source
V
s
I/O Connector
AIGND
AISENSE
ACH
+
Instrumentation
Amplifier
Measured
Voltage
V
m
–
+