How much experience to you have with DAQmx? Have you "played" with your device using MAX, the Measurement and Automation eXplorer? MAX (and DAQmx) allow you to set up a task to take multiple channels of data from a Device, calibrating the channels individually. It might behoove you to explore your Device using MAX, specifically to see how to set up acquisitions from all three channels at once.
The Example Code you copied was for a single Channel, and probably has more Bells and Whistles than you need. My advice would be to first simplify the Example as much as possible to make it easier for you to understand and to test. Then define your Physical Channel input to be the AI channels of the Device you are using. Replace the scale/calibration value with an array of calibrations, and apply them (using a For loop) to the respective channels. Note that there is a single timing function (for the device), a single Start, a single Read, etc., since these are defined for a "three-channel device". The Read should give you an array-of-three output, either a 1D array of 3 waveforms (if you've chosen Waveform outputs) or a 2D array of Reals (if you've chosen to have your Channel output as an array of reals).
Bob Schor
