Appendix A Device-Specific Information
E Series User Manual A-88 ni.com
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 and Connecting Analog
Input Signals sections of Chapter 2, Analog Input, for more information.
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-74 shows the source type switch locations on the front
panel of the BNC DAQPads.
Figure A-74. BNC DAQPad Front Panel
Figure A-75 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-75. Analog Input Circuitry
FS GS
FS GS FS GS
FS GS
FS GS FS GS FS GS FS GS
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
2 4 6 8 1012141618202224262830
USER 2
USER 1
PWR
COM
CTR 0
OUT
EXT
REF
DAC 0
OUT
ACH 6 ACH 4 ACH 2 ACH 0
ACH 1
ACH 3
ACH 5ACH 7
DAC 1
OUT
PFI 0/
TRIG 1
FS
GS
FLOATING SOURCE GND REF SOURCE
FS GS
Source Type
Switch
Source Type
Switch
FS = Floating Source
GS = Grounded Source
AI
x
+
AI
x
–
GS
0.1 µF
5 kΩ
AI GND
FS
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