Differential Connections For Ground-Referenced Signal Sources - National Instruments PXI-6070E User Manual

Differential Connections for Ground-Referenced Signal Sources

© National Instruments Corporation
Therefore, half as many DIFF channel pairs are available compared to
individual channels.
Use DIFF input connections for any channel that meets any of the following
conditions:
• The input signal is low-level (less than 1 V).
• The leads connecting the signal to the device are greater than 3 m
(10 ft.).
• The input signal requires a separate ground-reference point or return
signal.
• The signal leads travel through noisy environments.
DIFF signal connections reduce noise pickup and increase common-mode
noise rejection. DIFF signal connections also allow input signals to float
within the common-mode limits of the PGIA.
Figure 2-9 shows how to connect a ground-referenced signal source to a
channel on the device configured in DIFF mode.
Ground-
+
Referenced
V s
Signal
–
Source
Common-
+
Mode
V cm
Noise and
–
Ground
Potential
I/O Connector
Figure 2-9. Differential Connections for Ground-Referenced Signal Sources
AI +
AI –
Input Multiplexers
AI SENSE
AI GND
E Series Device Configured in DIFF Mode
2-23
Chapter 2 Analog Input
Instrumentation
Amplifier
+
PGIA +
V m Measured
–
Voltage
–
E Series User Manual