National Instruments NI 783xR Manuel D’Utilisation

© National Instruments Corporation

 

Figure 2-5.  Differential Input Connections for Ground-Referenced Signals

With this connection type, the instrumentation amplifier rejects both the 
common-mode noise in the signal and the ground potential difference 
between the signal source and the NI 783xR ground, shown as V

cm

 

in Figure 2-5. In addition, the instrumentation amplifier can reject 
common-mode noise pickup in the leads connecting the signal sources to 
the device. The instrumentation amplifier can reject common-mode signals 
when V+

in

 and V–

in

 (input signals) are both within their specified input 

ranges. Refer to Appendix A, 

, for more information about 

input ranges.

Figure 2-6 shows how to connect a floating signal source to a channel on 
the NI 783xR configured in DIFF input mode.

DIFF Input Mode Selected

–

+

–

+

–

+

–

+

V

cm

V

s

Ground-

Referenced

Signal

Source

Common-

Mode

Noise and

Ground

Potential

I/O Connector

AISENSE

AIGND

V

m

Measured

Voltage

Instrumentation

Amplifier

AI+ 

AI–