Connecting Differential Voltage Signals

You can connect grounded or floating differential signal sources to the NI USB-7845R. Connect the positive voltage signal to the AI+ and the negative voltage signal to AI-. To connect grounded differential signals to the NI USB-7845R, you must also connect the signal reference to AI GND.

To connect floating differential signals to the NI USB-7845R, 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-7845R does not read data accurately.