Appendix A
Device-Specific Information
A-16
ni.com
Figure A-6.
FS/GS Switch
Fig
u
re A-7 shows the analog inp
u
t circ
u
itry on the USB-6212/6216
BNC. When the switch is set to the FS position, AI
x
– is gro
u
nded
thro
u
gh a 0.1
μ
F capacitor in parallel with a 5 k
Ω
resistor.
Figure A-7.
Analog Input Circuitry
•
Single-Ended Mode
—For each BNC connector that yo
u
u
se for two
single-ended channels, set the so
u
rce type switch to the GS position.
This setting disconnects the b
u
ilt-in gro
u
nd reference resistor from the
negative terminal of the BNC connector, allowing the connector to be
u
sed as a single-ended channel, as shown in Fig
u
Figure A-8.
Single-Ended Channels
F
S
G
S
AI 0
AI
x
+
AI
x
–
G
S
0.1 µF
5 k
Ω
AI GND
F
S
+
–
U
S
B-621
x
Device
Flo
a
ting
S
o
u
rce
AI
x
+
AI
x
–
G
S
0.1 µF
5 k
Ω
AI GND
F
S
+
–
U
S
B-621
x
Device
Gro
u
nd-
Referenced
S
o
u
rce
AI
x
+
–
AI
x
+8
U
S
B-621
x
BNC Device
Gro
u
nd Ref.
S
o
u
rce (G
S
)
