NI 9215 Operating Instructions and Specifications
12
ni.com
To connect floating differential signals to the NI 9215 with screw
terminal, yo
u
m
u
st connect the negative lead of the signal to COM
thro
u
gh a 1 M
Ω
resistor to keep the voltage so
u
rce within the
common-mode voltage range, as shown in Fig
u
re 5. If the voltage
so
u
rce is o
u
tside of the common-mode range, then the NI 9215
does not read data acc
u
rately. The NI 9215 with BNC has internal
circ
u
itry that keeps the voltage so
u
rce within the common-mode
range. For more information abo
u
t the common-mode voltage
range, refer to the
section.
Figure 5.
Connecting a Floating Differential Voltage Signal to the
NI 9215 with Screw Terminal
1 M
Ω
Resistor
NI 9215 with
Screw Terminal
AI+
AI–
COM
Voltage
Source
+
–