NI USB-6259 Differential Input BNC Channel Assignments

[LEP_505]

The NI documentation for the NI USB-6259 does not define the differential input pairs for implementing a differential measurement.  There are BNC Inputs AI0 to AI7 and a second group of AI16 to AI23.   It would seem that one possible differential pair would be AI0 (+ input) and AI16 (- input).   There is no clear definition of which BNC input pairs to use for differential. 

[ZYOng]

The BNC variant of USB-6259 only supports 16 differential AI but not 32 single-ended. Each BNC port has both +ve and -ve pins connected.

Here is the description of the hardware.

780114-01: NI USB-6259 (16 Differential Analog Input, 1.25 MS/s) M Series Multifunction DAQ Device, BNC Term, U.S. (120 V), NI-DAQmx driver software and Signal Express LE

• National Instruments recommends using the NI USB-6363 for all new applications.
  16 differential BNC analog inputs (16-bit); 1.25 MS/s single-channel (1 MS/s aggregate)
  4 BNC analog outputs (16-bit, 2.8 MS/s); 48 digital I/O (32 clocked, 8 BNC); two 32-bit counters