Hi Stephan. The NI-DAQ function call you'll need to use is "SCXI_Strain_Null". The following is a description of the arguments within this call:
(SCXIchassisID, moduleSlot, moduleChan,DAQdeviceNumber,DAQchan,imbalance). Most of the arguments are self explanatory and can be found in the NI-DAQ Function Reference Manual. However, the "imbalance" argument is what you're after to do the characterization of each sensor. When called, this imbalance argument will return the ratiometric error of Wheatstone Bridge elements. They will be given as the ratio of the uncorrected bridge output voltage to the bridge excitation voltage.
jerry