User's Manual

Chapter 3 Connecting the Signals
DAQCard-1200 User Manual 3-8 ni.com
You should use the DIFF input configuration when any of the following
conditions are present:
• Input signals are low level (less than 1 V).
• Leads connecting signals to the DAQCard-1200 are greater than 15 ft.
• Any input signal requires a separate ground-reference point or return
signal.
• The signal leads travel through noisy environments.
Differential signal connections reduce noise pickup noise and increase
common-mode noise rejection. With these connections, input signals can
float within the common-mode limits of the input instrumentation
amplifier.
Differential Connections for Floating Signal Sources
Figure 3-3 shows how to connect a floating signal source to a
DAQCard-1200 that is configured for DIFF input mode. Configuration
instructions are included in the Configuring Analog Input section of
Chapter 2, Installing and Configuring the DAQCard-1200.