Figure 4. Connecting Non-Referenced Single-Ended Signals to the NI USB-7846R
PGIA
ADC
AI+
NI USB-7846R
Connection
Accessory
AISENSE
AIGND
V
cm
V
1
+
–
+
–
Overvoltage
Protection
AI–
Overvoltage
Protection
Overvoltage
Protection
Connecting Differential Voltage Signals
You can connect grounded or floating differential signal sources to the NI USB-7846R.
Connect the positive voltage signal to the AI+ and the negative voltage signal to AI-. To
connect grounded differential signals to the NI USB-7846R, you must also connect the signal
reference to AI GND.
Figure 5. Connecting Grounded Differential Signals to the NI USB-7846R
PGIA
ADC
AI+
NI USB-7846R
Connection
Accessory
AISENSE
AIGND
V
cm
V
1
+
–
+
–
Overvoltage
Protection
AI–
Overvoltage
Protection
Overvoltage
Protection
To connect floating differential signals to the NI USB-7846R, you must connect the negative
and positive signals to AI GND through 1 MΩ resistors to keep the voltage within the
common-mode voltage range. If the voltage source is outside the common-mode voltage
range, the NI USB-7846R does not read data accurately.
NI USB-7846R User Manual
|
© National Instruments
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