Connecting Differential Voltage Signals
You can connect grounded or floating differential signal sources to the NI PXIe-7858R.
Connect the positive voltage signal to the AI+ and the negative voltage signal to AI-. To
connect grounded differential signals to the NI PXIe-7858R, you must also connect the signal
reference to AI GND.
Figure 4. Connecting Grounded Differential Signals to the NI PXIe-7858R
PGIA
ADC
AI+
NI PXIe-7858R
Connection
Accessory
AISENSE
AIGND
V
cm
V
1
+
–
+
–
Overvoltage
Protection
AI–
Overvoltage
Protection
Overvoltage
Protection
To connect floating differential signals to the NI PXIe-7858R, 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 PXIe-7858R does not read data accurately.
Figure 5. Connecting Floating Differential Signals to the NI PXIe-7858R
PGIA
ADC
AI+
NI PXIe-7858R
Connection
Accessory
AISENSE
AIGND
V
1
+
–
Overvoltage
Protection
AI–
Overvoltage
Protection
Overvoltage
Protection
Analog Output
The NI PXIe-7858R provides connections for eight analog output channels. Each channel has
an AO pin and AOGND pin to which you can connect a load.
NI PXIe-7858R User Manual | © National Instruments | 5
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