User`s guide

22 • Signal Connections
Referenced Single-ended (RSE) Mode
In referenced single-ended mode, all the input signals are connected to the
ground provided by the DAQ/PXI-22XX. It is suitable for connections with
floating signal sources. Figure 5 shows an illustration. Note that when more
than two floating sources are connected, these sources will be referenced
to the same common ground.
AIn
AIGND
n = 0, ...,63
Floating
Signal
Source
Instrumentation
Amplifier
To A/D
Converter
Input Multipexer
V1
V2
+
-
+
-
CN1
Figure 5: Floating source and RSE input connections
Non-Referenced Single-ended (NRSE) Mode
To measure ground-referenced signal sources, which are connected to the
same ground point, you can connect the signals in NRSE mode. Fig 6 il-
lustrates the connection. The signals local ground reference is connected
to the negative input of the instrumentation Amplifier (AISENSE pin on CN1
connector), and the common-mode ground potential between signal
ground and the ground on board will be rejected by the instrumentation
amplifier.
Figure 6: Ground-referenced sources and NRSE input
connections
3.2.2.2 Differential input mode
The differential input mode provides two inputs that respond to signal
voltage difference between them. If the signal source is ground-referenced,
the differential mode can be used for the common-mode noise rejection.
Figure 7 shows the connection of ground-referenced signal sources under
differential input mode.
Figure 7: Ground-referenced source and differential input
Fig 8 shows how to connect a floating signal source to the DAQ/PXI-22XX
in differential input mode. For floating signal sources, you need to add a