National Instruments Data Acquisition Device E Series User Manual page 207

Appendix A Device-Specific Information
E Series User Manual
Differential Signals
To connect differential signals, determine the type of signal source you are
using: a floating signal source or a ground-referenced signal source. Refer
to the Differential Connection Considerations
Input Signals sections of Chapter 2,
AI signals.
To measure a floating signal source, move the switch to the FS position. To
measure a ground-referenced signal source, move the switch to the GS
position. Figure A-57 shows the source type switch locations on the front
panel of the BNC DAQPads.
FS = Floating Source
GS = Grounded Source
USER 2
PWR COM
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
USER 1
FS GS
Figure A-57. BNC DAQPad Front Panel
Figure A-58 shows the analog input circuitry on BNC DAQPads. When the
switch is in the FS position, AI x – is grounded through a 0.1 μF capacitor
in parallel with a 5 kΩ resistor.
Figure A-58. Analog Input Circuitry
Analog
CTR 0 EXT DAC 0
OUT REF OUT
PFI 0/ DAC 1
TRIG 1 OUT
FS GS
GS
FS
FLOATING SOURCE GND REF SOURCE
AI x +
AI x –
GS
FS
0.1 µF 5 kΩ
AI GND
A-72
and Connecting Analog
Input, for more information on
Source Type
Switch
ACH 6 ACH 4 ACH 2 ACH 0
FS GS FS GS FS GS FS GS
ACH 7 ACH 5 ACH 3 ACH 1
FS GS FS GS FS GS
Source Type
Switch
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