1. To get the Raw
Data you can use the DAQmxReadRaw function. I would take a look at the NI-DAQmx
C Reference Help for some more information about this function. I am unfamiliar
with that NiDAQmxAnalogUnscaledReader example that you were
referring to, and was unable to locate it, so I cannot tell you much about it.
You are a little off on how the data is coming in. The board returns14 bits all the time (single channel, or multi-channel). But when doing multi-channel only 13 bits of accuracy can be counted on, essentially there isn’t enough settling time for the last bit to be guaranteed accurate. The returned data is 14 bits, two’s compliment, MSB representation. So an unsigned int16 should be just fine. At 0V you should be reading 0s.
For more information about:
Hope that helps out.